If you’d like to start a new exercise program, pick any sport or activity that uses continuous motion (such as running, fast walking, cycling, swimming, skating, rowing, dancing) that you think you might enjoy. Start out at a relaxed pace until your muscles feel heavy and then stop. For the first several days or weeks you may be able to exercise only for a few minutes. Increase the amount of time gradually until you can exercise 30 minutes a day at a relaxed pace and not feel sore. Take a day off or go very easy any time you have any muscle soreness.
If you're happy with this program, you don't need to go any further. However, if you want to improve, follow the training methods that competitive athletes use. When a 30-minute session is easy for you, you are ready to begin training for fitness. Try to increase the intensity of your exercise on one day a week. Do your jogging, cycling or whatever you have chosen as your sport at a slow pace to warm up. Then gradually increase the pace until you start to feel short of breath and your muscles start to feel sore, and then slow down. Then when you recover, pick up the pace again. Repeat these surges until your muscles start to stiffen and then quit for the day. Take the next day off and go easy the rest of the week. Then once a week, keep on making your one-day-a-week hard workout harder and harder. You will be continuously increasing your level of fitness.
Before you start any new exercise program, check with your doctor to make sure that you do not have anything wrong with your heart or blood vessels. Intense exercise won’t hurt a healthy heart, but it can increase your risk for a heart attack if you already have a damaged heart.