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The duration of each session depends on the intensity. Lower-intensity training should continue 30 minutes or more; higher-level intensity exercise, 20 minutes or longer.

If you can't manage 20 consecutive minutes at first, start with 10-minute increments and space them throughout the day.

Do exercises that raise your heart rate 60 percent to 90 percent of your maximum heart rate. For maximum heart rate, subtract your age from 220. If you're getting started, shoot for 60 to 70 percent of that maximum. If you're moderately fit, try 70 to 80 percent; if highly fit, 80 to 90 percent.

To improve muscle strength, endurance and flexibility, make resistance training an integral part of a fitness program.

Eight to 10 exercises that condition major muscle groups should be performed two to three times a week.

Flexibility training helps develop and maintain range of motion. Perform stretching exercises for major muscle groups two to three times a week.

— Copley News Service