In fact, until you actually stretch your chest, you may not know just how tight those muscles are. With this stretch, you can really open up through the chest while also stretching the front of the shoulders. Oh, and it feels good too. To keep this move safe and effective, only rotate the arms back as far as they can comfortably go. Use the band for support while you stretch and avoid jerking or bouncing, which could cause an injury. If you have any shoulder or rotator problems, you may want to skip this exercise.
Do it right: Sit or stand and hold a resistance band with the hands wide. Take the band over the head and pull the hands apart, taking them down and just slightly back to gently stretch the chest. Adjust your hand position if you need more or less tension on the band. Hold for 10-30 seconds and repeat as often as you like.



I also find placing my hands on my hips and having someone pull my elbows gently backwards helps me stretch my chest effectively
Fitness Forum
I find it very relaxing after doing it few times.