Do crunches to tone your belly.
NEW THINK"Performing crunches on a stability ball allows a greater range of motion and calls on more muscles to help you stay balanced," says Stuart McGill, Ph.D., a professor of spine biomechanics at the University of Waterloo in Canada. This is only true if you put the ball in the correct spot, though. A study published in the Journal of Strength and Conditioning Research found that using a stability ball significantly increased abdominal activity only when the ball was placed under the lower back. Centering it under the shoulder blades was less effective than doing crunches on the floor.
If your middle's weak, do four sets of 20 crunches on a ball with 30 seconds of rest between sets. As you get stronger, increase the number of reps or decrease the rest period. If you want to create firmer, more visible muscles, hold a 10- to 15-pound dumbbell or weight plate against your chest and do three sets of eight crunches on the ball, with up to three minutes of rest between sets. Finally, add core moves, such as plank pose, to challenge your abs and back and help stabilize your spine during daily activities.
Perform walking lunges to strengthen your legs and butt.
Use jumping and bounding exercises (plyometrics) instead.
While many athletes rely on plyometrics to improve their power (a muscle's ability to quickly produce force), incorporating them into your routine can help you tone up faster and ultimately make your workouts feel easier. Jumping moves are also excellent bone builders, but do your joints a favor and perform them on a soft surface, such as grass or a mat.
Do moderate intensity cardio to burn fat.
Boost the intensity—but not too often.
While exercising at a moderate level does melt calories, the harder you push, the more calories and fat you'll blast. But vigorous sessions are physically demanding, so you shouldn't do them every day. To get a high calorie burn you can maintain, spend most of your workout time at your lactate threshold, or LT, which is your fastest sustainable aerobic speed. Depending on your fitness level, that can be anywhere from 60 to 80 percent of your maximum heart rate (go to here to see how to estimate your max heart rate) —or a rate of perceived exertion (RPE) of about 7. Exceed this intensity and fatigue sets in rapidly. Research has shown that the highest rate of fat burn occurs at or slightly below your LT. "Working out at this level teaches your muscles to use more fat during exercise," says Todd A. Astorino, Ph.D., an assistant professor of kinesiology at California State University San Marcos.
Here's how to do it: After a 5- to 10-minute warm-up, exercise for 15 to 20 minutes at your LT. (You might have to experiment to find a level that feels hard but sustainable.) Finish with a 5- to 10-minute cool down. If you can't maintain your LT for 15 to 20 minutes, break up your workout into shorter segments with rests: Do five minutes at your LT, rest for one minute, and repeat three times. Build up to 20 solid minutes.