Remember that nobody is in charge of your happiness except you.
While some work environments are inherently difficult, if you're consistently miserable it's your fault. You owe it to yourself and your coworkers to either find a job that makes you happy or make the best of the job you've got.
Smile and laugh more frequently.
Contrary to popular belief, smiling and laughter are not the RESULT of being happy; they're part of a cycle that both creates and reinforces happiness. Find reasons to smile. Never, ever suppress a laugh.
Don't waste precious energy on malice and gossip.
Before you tell a story about anybody else, or listen to such a story, ask yourself four questions: 1) Is it true? 2) Is it kind? 3) Is it necessary? and 4) Would I want somebody telling a similar story about me?
Don't worry what others think about you; it's none of your business.
You can't mind read and you don't have everyone else wired into a lie detector. Truly, you really have NO IDEA what anyone is REALLY thinking about you. It's a total waste of time and energy to try.
Remember that however bad (or good) a situation is, it will inevitably change.
The nature of the physical universe is change. Nothing remains the same; everything is, as the gurus say, transitory. Whether you're celebrating or mourning or something in between, this, too, will pass.
Trash everything in your work area that isn't useful or beautiful.
Think about it: you're going to spend about a third of your waking adult life at work. Why would you want to fill your work environment--and that part of your life--with objects that are useless and ugly?
Believe that the best is yet to come, no matter what.