Foam rolling is your friend. When you exercise you are breaking down your muscles so they build back up stronger than before. One of the side effects to this action is the development of scar tissue in the muscles and tendons. Stretching can keep some of the compounding effects of scar tissue development from keeping you on the side lines but once scar tissue develops in the muscle, stretching has a hard time getting it to go away. Foam rolling or any personal massage too