Fitness experts offer advice on how to get fit, refuel, and be back at your desk within an hour

We all know exercise is good for us, but with our hectic lives, workouts often land at the bottom of our to-do lists. Fortunately, you don't need to spend hours sweating on a treadmill to reap the benefits of exercise. In fact, many fitness professionals now recommend shorter bouts of intense activity. According to the American College of Sports Medicine, you should exercise aerobically three to five times each week, maintaining intensity for 30 to 45 minutes. The American Council on Exercise points out that you can accumulate this time throughout the day. For example, if you walk briskly for 20 minutes at lunch and take another ten-minute walk after dinner, you've exercised for the recommended minimum of 30 minutes. This makes squeezing in a workout between meetings easier than ever.

To help you incorporate exercise into your busy schedule, we asked personal trainers to offer advice on programs that can be done during a lunch break. Each routine takes only 40 minutes or less to complete, so you'll have plenty of time to work out, grab a bite (don't forget to eat and hydrate), and get back to business in about an hour.

Lunchtime Workout #1: No Gym Membership Required

Getting a heart-pumping, muscle-burning workout doesn't necessarily mean belonging to a health club. Using what's around you at the office or at home—a staircase, the floor, or even soup cans in place of hand weights—can be all you need to get fit. For the perfect do-it-yourself workout, we consulted personal trainer Aron Branam, fitness director at the Seattle Athletic Club Downtown, who created the following combination cardio and strength workout you can do in less than an hour. "With minimal rest periods between exercises, you'll build muscle endurance and get your heart rate up," explains Branam, without losing too much of your scarce free time.

All you need for this workout is a set of stairs and either a floor or a wall, depending on your fitness level. Remember to keep moving and try to maintain between 65 percent and 80 percent of your maximum heart rate. (Beginners should stay in the lower end of this range; maximum heart rate equals 220 minus your age.) Pick two days a week to perform the following nine exercises, but don't do this routine on adjacent days. On off days, Branam suggests, take a brisk walk, ride a bike, or simply ascend the steps in your building for about 35 minutes.

Stair climb. Begin by walking up the stairs, stepping only on every third step. Do this at a comfortable pace until you reach the top. (Depending on your fitness level or the time available, ascend one to four flights of steps.) Descend normally one step at a time. Then climb the steps again, this time landing on every other step. Descend normally. Finally, ascend the steps one at a time. As you decrease the number of steps you skip, increase your pace so you're moving briskly by the third climb.

Exercise #1
Traditional push-ups, five reps. Get into the push-up position with either your knees or the balls of your feet touching the floor. (For beginners, stand facing a wall with your hands shoulder-width apart on the wall.) Bending your elbows, lower your chest to the floor or the wall, keeping your back flat and your buttocks down.

Exercise #2
One-legged squats, ten to 12 reps. Facing the left wall near the bottom of a flight of stairs, place your right foot two steps up from the floor. Keeping your heels on the floor and your shoulders over your hips, bend your knees as if you're about to sit in a chair. Do not allow your knees to come forward over your toes, and never let your glutes drop below your kneecaps. Return to your starting position and repeat for ten to 12 reps. Switch sides, placing your left foot on the stairs, and do ten to 12 reps.

Exercise #3
Staggered push-ups, eight to ten reps. Get into the push-up position you chose in exercise number one (with your hands either on the floor or on the wall in front of you). Place your hands at least shoulder-width apart, then slightly move the right hand forward so that your hands are staggered. Lower your chest to the floor or the wall, then return to the starting position. Repeat for eight to ten reps. Switch sides, placing your left hand forward, and do eight to ten reps.

Exercise #4
Side stair step-ups, one to four flights of stairs (depending on time and fitness level). Face the left wall at the bottom of the staircase. Place the right foot up one to two steps. Keep the leg on the floor fully extended. Use the right leg to raise your body until you can place both feet on the same step. For balance, either hold onto the railing or slightly touch the wall with your fingertips. Continue up the staircase, moving your right leg up first, then your left, until you reach the top. Walk down to the bottom and repeat the process starting with your left leg.

Exercise #5
Triceps push-ups, eight to ten reps. Get into your push-up position (using a wall or the floor). Place your hands less than shoulder-width apart and, keeping your chest over your hands, lower your chest to the floor or to the wall. Keep your elbows in close to your body to work your triceps. The closer together you place your hands, the harder this exercise becomes.

Exercise #6
Crossover step-ups, one to four flights of stairs. Face the left wall at the bottom of the stairs so that your right leg is closest to the steps. Cross your left leg over the right one, placing it one or two steps up from the floor. Using your left leg as the driving force, raise your body to this higher step, keeping your weight forward over your left foot the entire time. Repeat until you reach the top of the stairs. Walk to the bottom and repeat on the opposite side.

Exercise #7
Abdominal crunch, 15 reps. Lying on your back with your knees bent and your feet flat on the floor, cross your hands over your chest and keep your eyes on the ceiling. Use your abdominals to lift your shoulder blades off the ground as you exhale. Pause, then return to the floor. Repeat.

Exercise #8
Oblique crunch, 20 reps, ten on each side. Begin in the same position as for exercise seven, but when you lift your shoulder blades off the ground, twist the torso to the left and reach the right hand to the left knee. Return to the starting position and repeat, reaching to the opposite side.

Exercise #9
Plank. To work your abdominals and lower back, lie on your belly with your legs fully extended. Prop your elbows under your shoulders and tuck your toes under. Lift your body so that your weight is resting on your forearms and the balls of your feet. Hold this position for 20 to 30 seconds.

Lunchtime Workout #2: The Ideal Gym Routine

For those who hit the health club during their lunch hour, we've asked Elanna Schwab, certified personal trainer and part-owner of Main Line Health and Fitness in Bryn Mawr, Pennsylvania, to recommend the perfect get-fit-quick gym routine. The following workouts involve machines found in most health clubs. "If you've only got 30 to 40 minutes to work out, you must focus on the quality, not quantity, of your exercises, as intensity will yield maximum results," explains Schwab, who advocates working out in a way that overloads and stimulates the muscles. That's why she suggests just one set per strength-training exercise. Doing each set slowly and to failure—meaning the pertinent muscle group is exhausted at the end of eight to 12 reps—intensifies the exercise so you get maximum results in a minimum amount of time.

Even though weight training is the basis for two out of five workout days, Schwab suggests that you get your heart pumping on those days also by not taking breaks between exercises. And because her regimen is a total machine workout, you save time by not having to do a ton of stretching, because "machines work your muscles' full range of motion, which ultimately helps with flexibility." In addition to machines, however, Schwab strongly suggests finding time to take a yoga or a Pilates class at least once a week, whether it's on a Saturday morning or on your way home from work.

The following workout regimen includes two days of resistance training with machines (on Mondays and Thursdays) and three days of cardio exercise (on Tuesdays, Wednesdays, and Fridays). When resistance training, remember to perform one set of eight to 12 repetitions per exercise and do each rep slowly and to failure, then quickly move on to the next piece of equipment. Should your facility not offer some of the following pieces of equipment, ask a fitness professional to offer an alternative.

Mondays and Thursdays (resistance training, eight to 12 reps per exercise)
Exercise #1: hip extension
Muscles worked: glutes

Exercise #2: leg extension
Muscles worked: quadriceps

Exercise #3: leg curl
Muscles worked: hamstrings

Exercise #4: leg press
Muscles worked: entire lower body

Exercise #5: (Monday) seated row/(Thursday) lat pull-down
Muscles worked: lats and torso

Exercise #6: (Monday) women's chest fly (sometimes called ten-degree press)/(Thursday) lateral raise
Muscles worked: pectoralis major (chest)/deltoids (shoulders)

Exercise #7: pull-over
Muscles worked: latissimus dorsi (back)

Exercise #8: (Monday) bench press/(Thursday) overhead press
Muscles worked: pectoralis minor (chest)/secondary shoulder muscles

Exercise #9: (Monday) assisted chin-ups/(Thursday) bicep curls
Muscles worked: upper body/biceps

Exercise #10: (Monday) assisted dips/(Thursday) tricep extensions
Muscles worked: chest and triceps/triceps

Exercise #11: abdominal crunch machine
Muscles worked: abdominals

Exercise #12: lumbar extension
Muscles worked: lower back

Tuesdays, Wednesdays, and Fridays (cardio exercise)
Choose a piece of cardio equipment, such as a treadmill, a stair stepper, a stationary bike, or an elliptical machine, and exercise for 30 to 40 minutes. Try to work a majority of the time at an intensity between 65 percent (beginners) and 80 percent (advanced) of your maximum heart rate. (Maximum heart rate equals 220 minus your age.)

Quick Exercises To Do At Your Desk

OK, so you may get some funny looks if you start working out in your cube—but remember, every little bit counts. "Even if you can only exercise a little each day, it still makes a huge difference to your overall mental and physical health," says Meri Hurst, a certified personal trainer and co-owner of the Training Zone in Atlanta. All you need for the following exercises, recommended by Hurst, are an eight-inch ball (one that's firmer than a Nerf but softer than a soccer ball) and hand weights. Both are inexpensive, and you can easily store them in a desk drawer. To make any of these exercises more challenging, slow the cadence of each repetition.

Exercise #1: Leg extensions
Muscles worked: Quadriceps and core
Reps: Two sets, 15 reps each side
Sit up tall on the edge of your chair (or on the edge of your desk if your chair rolls) with your shoulders over your hips. Keeping your rib cage lifted, raise your left leg off the chair, draw your navel in, and exhale. Next, extend your leg forward, keeping your toes pointed. Pull the leg back in and return the foot to the floor. Repeat. Switch sides.

Exercise #2: Ball squats
Muscles worked: Lower body
Reps: Two sets, 15 reps each
Standing up straight with your back to your chair, place the ball between your legs about an inch and a half above your knees. Cross your arms and place your hands on your shoulders. Lifting your rib cage and drawing your navel in without tucking your tailbone, sit back on your heels and lower your buttocks until it touches your chair. Engage your inner thighs by not letting the ball drop, and return to the starting position. Repeat.

Exercise #3: Biceps curls
Muscles worked: Biceps
Reps: Two sets, eight to ten reps
Sit on the edge of a stationary chair. Holding your hand weights, begin with your arms straight down by your sides. Keeping your elbows in close to your body with your rib cage lifted and your navel in, lift the weights so your hands come toward your shoulders. Lower to starting position.

Freelance writer Kelli Rosen, a certified personal trainer and Spinning instructor, keeps extra workout clothes and a spare pair of running shoes in her car so she's always ready for a workout.