Stress management in the workplace starts outside the workplace. Get enough rest, both mentally and physically. If you are aware of any relevant character flaws you have, work on improving them.
The next step is to spend some time in the workplace in a relaxed manner. Get there a bit earlier, leave a bit later. Personalize your workspace. Clarify what your duties and responsibilities are if necessary. Spend some time socializing (even if you don't especially like the people). Being able to understand, communicate to and rely on each other goes a long way to reducing or even eliminating stress in the workplace.
Don't hold grudges, don't waste time on sucking up, don't let other roll over you. Against certain kind of people a show force is necessary to gain respect - don't let this phase you, treat it as a necessary form of communication.
When work environment related problems are solved, you can focus on the work itself without distractions. Know your limits and keep an eye on your health (both mental and physical). Take short breaks, even if only 10 seconds for a deep breath. (If you're a smoker, quit! Smoking adds to stress instead of reducing it.)
Stress management in the workplace is straightforward and easy if you have both the physical and social work environment sorted out.