Here are a few strategies for de-stressing:
1) Practice mindful breathing.
Sounds so basic, but "mindful breathing" is an effective way to feel more relaxed almost immediately. You can read a detailed explanation of the three breathing exerises by Dr. Weil here. My favorite is the relaxing breathing exercise shown in the animated gif below:
2) Set reasonable goals and expectations.
Recent research has shown that if you lower your expectations you are happier. Sounds crazy, right? But I think the important part of this concept is to make your goal setting practical. Figure out what are reasonable goals and work towards that.
3) Take care of yourself first.
Maybe I should have put that at the top of the list. It's the same idea as the the flight attendant's say, "Put on your oxygen mask first before assisting others."
4) Have something to look forward to.
If you build in a reward—it doesn't have to be big—then the mental activity of looking forward to this idea actually helps you stay more positive and lowers your stress. Best of all, if the reward is an activity that is healthy and gives you more energy, then you accomplish two things at once. For me a simple reward like taking a short (or long) walk outside helps when I have a long day at my desk. Focusing on a bigger reward such as a trip you are planning or even a fun Saturday activity helps too.
If you can't see the breathing exercise in the animated gif above, click on the image below to see the steps to the exercise.