the first step is just bringing some awareness to the situation. just noticing - hey, i'm totally pissed off right now. and realizing that the "pissed off" attitude is not you. it's just something your experiencing, a shifting, changing, fleeting emotion that can be dealt with any way you choose. i know, easier said that done, but just breathing some space between you and the negative emotion will help it dissipate faster.
now, that you've recognized the emotion, don't judge yourself or beat yourself up for feeling blue, or angry or annoyed. instead, just breathe. that's right - just breathe. you've heard that one before, right? turning to the breathe, and consequently quieting the mind is one of the most effective tools for moving beyond difficult emotions. as you breathe, you may begin to feel the sharpness of the emotion begin to dull and begin to slowly melt away.
from there, slow down. i find that my negative emotions are often coupled with a propensity for rushing and not being present, which in turn makes me more frustrated, because i'm not being effective, efficient or present. when i slow down, i see things more clearly.
next time funky feelings creep into your day, just notice them. recognize that they are not you and therefore can be changed. breathe and slow down. and everytime you consciously choose to move past your negative thought patterns, it will get easier - i promise.