The American College of Sports Medicine suggests doing 60 minutes of cardiovascular exercise 5 days a week—a notch above the 30 minutes, most days a week recommended by the Surgeon General to maintain overall health. “Shoot for 60 minutes a couple days a week to expedite weight loss and fitness gains,” says Dixon. If possible, select an outdoor route with hills to increase the challenge.

1. Warm up with an easy walk for about 5 minutes. Increase your speed for the next 5 minutes, pumping your arms more vigorously and taking smaller, quicker steps. For the next 20 minutes, use this pattern: Walk as fast as you can or jog for 3 minutes, recover for 2. On a scale of 1–10, where 1 is easy and 10 is impossible, try to keep the 3-minute intervals around a 6.

2. During the faster phases, maintain proper posture by keeping your chin up and directing your gaze at least 10 feet in front of you; if you look at the ground, your shoulders tilt forward, your back gets strained, and your muscles fatigue more quickly. Another way to help keep a straight spine: Pretend you have a balloon attached to the top of your head and it’s pulling you toward the sky. During the recovery, keep your form but slow your steps and recover your breathing.

3. For the next 10 minutes, do five 1-minute intervals at an effort of 8. Go hard [wouldn’t “all out” be 10?] for 1 minute, concentrating on keeping your feet quick and your steps small; then recover for 1. Repeat five times. Cool down for 10 minutes, gradually decreasing your speed.

Other 60-minute workouts:

>>Cardio Mix-Up: At the gym, start on your least favorite piece of cardio equipment: elliptical, stair climber, treadmill, bike. Do it for 20 minutes. Then switch to your next least favorite for another 20. End on your favorite for the final 20 minutes.

>>Get Schooled: Take a new class—Pilates, Body Pump, or one of the recommendations in “Fitness Trends, Fun Workouts,”—or get a new fitness DVD from the library to try at home.

>>Total Body: Start with 20 minutes of cardio, then do the 30-minute strength-training workout, and finish with 10 minutes of yoga.