We all have it, just some more then others. Whether its school, work, work out, health, kids, pets,etc, ITS there. Just knowing how to keep the little monster at bay can be a major life saver. For me anyway stress can mean a few things, overly eating when I'm not hungry and kicking back extra cocktail here and there. Obviously these two things are fine to a degree, but knowing when to stop to keep these items in check so you don't derail your fitness goals. Having an outlet to help with the stress, whether working out, running, hanging with friends, whatever really works for you great. For me anyway, kickin' it at the GYM before work and riding my horse truly calms me down and makes me whole.
So- Find your zen in whichever way possible. This can make a lot of difference getting frustrations and stress out in a healthy fashion rather then blowing up and going ape- shit on some co-worker. We all have done it ;)