I was the small skinny kid when I started muai thai at age 15. Pretty soon I was the small skinny kid who no one could beat up anymore.
I started not backing down. When you're skinny, people think they can push you around. They called me something, I called them something back. They pushed me, I asked them if that's all they got. They threw a punch, I dodged and hit them. A couple of years later, while drunk, it got me into a 5 vs 1 situation, the first fight I lost. I quit martial arts after that.
I recently started MA again, but at nearly age 30 I don't have all those youthful hormones raging around inside me anymore, I don't go places where people who are looking for a fight go anymore, and I've gotten very security conscious, so it's going to be different this time around
The confidence and security you get from becoming a good fighter is a big plus, that can turn into a minus. Other than that, it's just a sport, that's average on building strength and endurance, and excellent for flexibility, toughness and reflexes.
I never liked the traditional martial arts that are big on the mental aspects, focus on moves that are more gymnastic and aesthetic than effective, and so on. Practicing those perhaps gives you a different outlook.
