I love my job but work can be pretty stressful so I try to find ways to alleviate the stress before I even get to the office. I do this by sitting up as straight as I can in my car - having good posture - and I practice deep breathing for about five minutes. It's pretty basic but I start out my morning feeling relaxed and calm.
I know it sounds silly but living with chronic depression, I've taken just about any route i can to improve my mental health and the best thing so far funnily enough is to just clean. If i see an unwashed cup, grabbing it and cleaning it makes me feel a little better. Dusty floor? 5 minutes of sweeping and i feel a world better simply because i know i just accomplished something (even if it was small =P). One teensy tiny accomplishment in an otherwise empty day can make a world of difference =)
I am prone to flashes of anxiety, and I've found that if I do 30 push-ups (modified, regular, or wall), that forces me to regulate my breathing and focus on something else. By the time I hit 30, usually, the "flash" has passed, and I've done something physically positive for myself as well!
I make Mii's of challenging, aggravating people I encounter throughout the day on my Wii and box them when I get home. If I have a difficult co-worker, I'll Wii box them in the morning before I go to work and it keeps me smiling and killing them with kindness when they cross my path.