miniwarmthLike many of the comments above, I used to get visibly and verbally upset. Nowadays it takes an awful lot to push me to that point. That said, i think I keep a lot of it in and this too has a negative effect on my game.
The second most golfer's realize they are not good enough at the game to get mad I guarantee they play better! Having temper tantrums only hurts your psyche, I would know!
In college I was quite the hothead, then soon after graduating, of course I took the game less serious and started having more fun on the course. Not surprisingly, my scores started going lower and lower. Golf is a game and games are meant to be fun.
Bringing me to another point, "negative self talk" is one sure fire way to play your worse! The second you say I "can't do this or that on the course" I can bet you one thing, you won't accomplish what you are trying. Saying to yourself, "I STINK" or "I'm horrible" does not help either, replace it with "I could use some work on this aspect." A positive look at things can only help! Plus you will be far more pleasant to play with!
Read Zen Golf while you are at it!