Lots of people say its not good for your hair, but truthfully I don't think it matters. I take a shower everyday and I'm fine:) if this concerns you though you can wash your hair every other day but your body everyday.
Well you shouldnt wash your hair daily. It will get oily or dry, wash it only when its dirty. But washing your skin some people do daily, others not. Everyone has a different idea of how often they shower to meet the level of hygine they want. You can look it up on Google.
As you said, since you sweat a lot, you should probably shower every day. I sweat a lot, too, but sometimes I'll go the entire weekend without one because I don't really do anything on those weekends. However, I make sure that I shower whenever I can smell myself.
I take a shower once every three days (I exercise a lot and I don't recommend this for most people) and during the summer I shower every 2-3 weeks. (why did I answer this question? I'm such a bad example!)