Therapy Years after Injury

Hi–I have a question about the usefulness of starting therapy years after injury. I smashed just below my kneecap into a curb two years ago, resulting in a bone contusion. They gave me a ditto of exercises, but I did not do them because a) it was for runner’s knee, and I felt like the people at the urgent care were just grabbing something remotely related and it did not necessarily relate and b) it seemed to get better just fine and c) they were exercises–who wants to do those? The only thing is, I don’t know if it’s the rain or the cold, but during winter here in Portland, OR, it tends to hurt often…the impulse is to want to keep that leg stretched straight out, especially if I’m bending down. It’s a sort of dull, angry ache. So…my question is, realizing the most opportune time has long passed (and assuming the exercises would have helped), is there any point in doing them now to alleviate things? It’s not debilitating or anything, but I am concerned that at 37, the level of discomfort will become so when I am much older. If you suspect the exercises may be of use (I realize you cannot say definitively), what sort of schedule would you recommend, and should I also do them in the months where there is no pain? Thanks so much for your time,Andy