Listen to your favourite song. Music can have an excellent effect on stress levels.
Get Moving. Powering through a work out increases your health and your confidence. I have also noticed that going on a hike really reduces my stress.
Vent to someone who is going through something similar. Sometimes it is just good to get it off your mind.
Know when to take a step back. If you are feeling overwhelmed sometimes it is wise to take a small break from the task at hand and just relax.
Prepare for the day. If you know it is going to be a stressful day take a few minutes to get small things ready that will make your day run smoother. I have started picking out my outfit for the next morning the night before and it makes my mornings so much easier.