Depends on the fighting, I find it strengthens you as a person, I was bullied as a kid, I've adapted to that so nothing now offends me, and I am a fan of UFC and I train mma, beating someone up is easy, if they deserve it then do it.
Duh?!!!!!!!!! Unless if someone completely deserves it. Even then, there is always a way to stand up for yourself firmly without getting too violent. If you're talking about physically fighting with someone, then don't do it unless they do it first. Or if they're hurting a loved one.
It depends on how you fight. Fighting with physical contact or breaking things isn't healthy. But heated discussions are defiantly normal. It adds spice to the relationship. Just don't say or do anything you can't take back. Say only what is true.