Well, needless to say, I'm proud that you're demonstrating such initiative in getting yourself into better shape. Your heart and your self-confidence will thank you in the long run.

As for the erections, I'm glad you supplied us with some personal background info, but did you ever think that it just might be okay to get an erection in the presence of others? Doesn't sound like you're getting aroused from the company of the other men, so you don't have the sexuality to worry about. I keep hearing from other men that various states of arousal are common in the locker room. Chalk it up to increased blood flow, seriously; you've spent a significant amount of time in your work, and with your muscles getting the good workout, the following symptoms make sense: increased blood flow, awareness, a surge in active energy, rises in testosterone, protein synthesization... and a woody.

So don't worry about it. Unless someone gets in your face and gives you grief about it, just realize that nobody's too worried about your wood.