K: Know your limitations
There's nothing more stressful than getting in over your head. Before you accept a meeting or take on a project, check your schedule and evaluate the scope of what you're being asked to do. Only take on what you're sure you can manage -- and manage well.
L: Laugh it off
Studies have found that laughing can reduce stress and actually strengthen your immune system.
So, get crackin' (up, that is).
Take a coffee break or have lunch with funny co-workers and instead of griping about office politics or your workload, tell a few jokes. Once a few laughs come out, more will follow; it's contagious!