Stretching is a very important part of your exercise regimen. Stretching will increase flexibility and improve the range of motion of your joints.

Before stretching, warm up with five to ten minutes of light activity. Or reserve stretching for after a workout. Keep stretching gentle. Don't bounce. If you feel pain, you've stretched too far.
Hold a stretch for about 30 seconds, then switch sides and repeat. If you have a problem area or the stretch is particularly helpful for pain or discomfort, you may benefit from repeating the stretch.
If you have any health conditions or injuries, talk to your doctor or physical therapist about which stretches are right for you.

Try these exercises after your regular cardio or strength workout (aim to do them five times a week). You'll see improvement to your flexibility in as little as two weeks and gains in both your strength and endurance in less than one month.