Strength training includes exercises using your own body weight for resistance. Push-ups, for example, work your chest, arms, shoulders and upper body. Position yourself on your hands and feet with your eyes facing the floor. Place your hands slightly greater than shoulder-width apart and your feet comfortably apart. Keeping your back and legs straight, slowly bend your elbows and lower your chest until your chin reaches the ground. You'll feel tension in the muscles in your back, abdomen and upper arms. Then slowly return to the starting position. Repeat.