Don't sweat it. I had mine on Wednesday and everything's just fine. It kind of depends on your pain tolerance and how well you react to things, but I haven't had to take any painkillers at all. But I have a pretty high pain tolerance and don't feel pain as bad as some people. It doesn't really matter what you do before the surgery, but if you don't work out much, I wouldn't recommend starting right now, just because you would have the added pain from working out in addition to the surgery pain. The muscles would be tearing down and rebuilding themselves, and along with the rest of the area, that has the potential to be uncomfortable. But if you work out a lot and a few pushups wouldn't normally bother you, go for it. Just take it as it comes.
And usually the stitches aren't self-dissolving. Most surgeons will have you come back later and take them out.
Good Luck