Originally Posted by Freebase Dali

I messed around with it for a couple years at the Y with a cousin and some locals. Had an unofficial trainer for a few months. Never actually joined a real gym. But I think I would recommend an actual boxing gym with an actual trainer if you're serious about doing it for more than a hobby or just messing around here and there. If you're not really into it, I think it won't really play out the way you may want it to.

If you're willing to put in the work, you may as well join a gym. I wasn't, and I wish I had.
As far as what to expect... well... no matter how serious it is, I'd say to just take your ego out of it and treat it like any other sport. The less it is about proving yourself, the more you'll learn about actually taking yourself out of the equation and implementing technique. The goal is to learn a skill. You just have to accept that and give yourself over to the learning, and not the emotional urges.
I found that part the hardest to try and overcome when sparring. I'd forget what I'd learned because I just wanted to win, or I'd become angry because I wasn't winning, and all my sh*t would go out the door.
Overall, in any physical contest, expect competition. But don't feel threatened by it. It's simply motivation to become better, no matter what it is you're doing. And that is what you should embrace, whether your trainer tells you that or not.

Originally Posted by Croatian Masochist

Boxing is ok as a sport, but if you're looking at something more beneficial and fun, try Muay Thai or some other variation of basic kickboxing. Tae Kwon Do is also very fun (although difficult), but it's hard to find an authentic teacher sometimes.
Edit: I'm very biased because this my personal favourite, but Brazilian Jiu-Jitsu is very interesting, and legitimately helpful if you're in some 1 on 1 bar fight.