When you choose a new behavior, don't make it a punishment-make it a reward. Everyone responds better to rewards than threats. If you try to get yourself to do something by threatening yourself, you'll only get discouraged. If you reward yourself for new behaviors, you'll be more likely to practice them.
For example, you may try to get yourself to practice tennis even though you find it uncomfortable because you're not very good at first. If you tell yourself, “If I don't play tennis today, I don't get to watch a movie with my friends later,” you'll just get angry about the punishment you set for yourself and you'll want to avoid practicing tennis. But if you set a reward like, “If I play tennis today, I'll give myself time to play video games later,” you'll be more motivated to practice tennis.
In a way, this rule demonstrates a central theme of BA: people respond better to positive reinforcement rather than negative reinforcement. Part of the problem of a TRAP is that you respond badly to a punishment (of sorts) from the outside world. Don't beat yourself up! Give yourself positive reinforcement! In the fight to improve your behaviors and moods, be your own ally, not your enemy.