Listen to some good music, stuff that makes you feel powerfull and good. My favorite stress treatments are Death Metal and Death Grind your favorites will probably be different.
Also, During whatever time you have away from the office, take as much time as you can to do things that YOU like to do. Also, make sure you bum around and do nothing at least a few hours per week, it really feels good to just chill out and relax. Do something that is not productive, and that you would usually consider to be a complete waste of time. It has helped me from "burning out" in the past back when I used to work a lot of overtime. You could also treat the additional responsibillities at work as an opportunity to show your stuff, and to proove you are worth MORE to the company then they are paying you. Everytime I wind up in a big project, I bust my ass to get it done, and get it done right. During the time I'm doing it, it may be very difficult, however, I just remember that the better I do when something really counts, the sooner I'll get promoted, and the better increase I'll get during review time. Though that may seem like added pressure for some people, which I guess could hurt performance.