Monday and Friday

Warm-up: Light cardio on the treadmill, bike or elliptical. Five minutes

Circuit work: Alternate 10 reps each of two strength-training moves (see below) with one minute of moderate cardio; repeat three times. Alternate one minute of cardio with another two exercises; repeat three times. Alternate one minute of cardio with last two exercises; repeat three times. Beginners use 5- to 10-pound weights; veterans, 15- to 20- pounds. 18 minutes

Intense cardio: Alternate one minute of high speed (3.5 to 5 mph on a treadmill) at moderate resistance (an incline of 3 to 5) with one minute of low speed (2.5 mph) at low resistance (incline of 1 or 2). Repeat set three times. Six minutes

Cool down: Low-speed walk. One minute

Tuesday and Thursday

Same as above, but substitute strength-training moves. Try squat jumps, pushups, step-ups, wide-grip lat pull-downs, side bridges and crunches on the fitness ball.

Wednesday

Rest

Saturday and Sunday

Do 45 minutes of your favorite sport