The issue of sports being healthy for the fans really depends on the team you support I suppose. I support teams that are/were local to me. I have to say my mood is affected by how well the various teams I support are doing but only in extreme cases. For example when Ireland won the Six nations grand slam for the first time in 61 years( a BIG f*cking deal for Irish rugby fans) I was euphoric for weeks. On the opposite end of the scale when Henrys handball denied Ireland a place in the world cup I was pissed off and grumpy for about two weeks.

And regarding feelings towards rivals and their fans? That really for me depends on the the history and the age of the rivalry. The more traditional rivals I have more respect for but the newer ones I actively hate as the rivalry is more intense, mainly because the what will be considered the important history of the rivalry is being made.

I wouldnt swap being a fan for anything though. Watching my various teams on TV gives me something to do during the long weekend hours at the very least.