Anger. That's one serious problem I've had and though it is getting better, I'm still struggling with. I'm a perfectly happy person and I can take a joke as well as a next person, but when my 'angry button' is triggered, I go from sweet smiling cherub, to neck spinning chick in The Exorcist. The worse part of my anger is that if I open my mouth, anything can fall out. It is not easy to repair a friendship when you've called someone out during a moment of anger, I tell you.
When I was leaving secondary school, people wrote in my 'signing out' book that I should learn to control my temper and the things I say when I'm angry. My anger is not even anger anymore, it is blind rage.
Things are more improved now. My new thing for the past couple of years is mustering all my will power to make sure I keep quiet when I'm angry. It is working well but there's obviously still room for improvement and on the plus side, I don't get angry very often. So things are on the up and up.
That's one of the problems I've had (and still have)