What are stretches? Why stretch?
Stretching is the deliberate part of an exercise program where you try to increase your flexibility and improve the range of motion of your joints. Stretching is a way to get your muscles and joints moving, to improve your flexibility, to build strength, and to help your body relax and relieve stress.
What it does AND what it doesn't do.
Stretching builds flexibility and you can use the increase in your flexibility to build strength and cardio endurance. Stretching can often be done in smaller spaces and without the need for expensive equipment. Stretching, by itself, will not give you extra strength or allow you do run faster. However, when you combine strength and cardio activities with flexibility training your overall health improves.
Safety
Two important points. 1. Do not jerk your body to force a stretch. You will tear muscles this way. Build you range of movement slowly and steadily by doing more repetitions and not forcing your workout. 2. Do your stretches after a brief warmup or cardio workout (this will give your muscles time to warm up).
Focus One: After Warmup or Exercise
Here are some stretching activities for after a warmup or cardio workout.
Focus Two: In Your Class, at the Office, or at Home
Stretching at home or when you are in a classroom or office is an important habit to get into. Work you way through these links.

from Alberta Centre for Active Living