So what do you think are the best stretches for this? I've been playing with doing pushups to fatigue the muscles and then lying on the foam roller to stretch them. Seemed to work well, but I only just did it yesterday. I'm open to suggestions.

I've also done some of the lacrosse ball thing where I roll it along from the sternum, going outwards, just under the collar bone. The first time I screwed up used too much pressure.