I've been there many times. I think the best way is to just step away for a while and relax your brain. This could mean a day or two, a week, or a month. Also make sure to play within your bankroll. If you have a $200 bankroll don't play $100 tournaments. Limit it to no more than 5% of your bankroll.

The swings will drive you crazy. I've found that even a good swing can take it's toll mentally. I feel like I just want to keep playing since I'm doing so well, and then at the end of the day I'm completely worn down.