Stretching is slowly training your body to accept a greater range of motion. The more flexible you are the less you will get injured, the more powerful you will be, and the better you will feel.
Since stretching is about getting your body to accept (not forcing it to experience) a greater range of motion, perform each stretch by relaxing into it. While you may feel tension in your muscles during the stretch, you should not be pulling or jerking your body.
Start by getting into the the starting position of the stretch. Take a deep breath, hold it for one second, and then, as you slowly exhale, relax into the stretch position. Keep relaxing into the stretch until your body won’t allow you to go any further. Hold that position until you are finished exhaling. Once you’ve finished your exhale, breathe in again, hold it for one second, and, as you exhale, relax even further into the stretch.
Each time you repeat this cycle you should be able to relax your body a little further into the stretch. Repeat this process until you’ve performed the stretch for the allotted time.