What a great topic. I am a big fan of stress reduction and management. I often work for several weeks straight with not a day off, and have a lot of personalities to deal with on my team... when you know what works for you in terms of managing stress, it can really take you a long way and save your attitude from becoming sour.
TAKE A BREAK!
What really works for me when I'm stressed is to take myself out of the situation for 5 to 10 minutes. If I'm upset at my desk over something sitting in my inbox, I take my dog outside and take my iPhone with me to play a game of Scramble with Friends. If I'm feeling stressed because I don't know how to figure out a problem at work, I log into my Lumosity and play a few brain exercise games... when I come back from my 5 minute break, I feel mentally recharged.
ORGANIZE & PLAN
Another thing that really helps me when I'm stressed is to make a list. For example, if I feel that I have no time because my workload is too heavy, I'll leave my home office to sit at my kitchen table. I'll make a list of all the things that need to be done. Even though, in theory, it takes time to make this list that may have been spent doing a task, you'll amp up your productivity because all of these overwhelming tasks were IN YOUR HEAD! And now it's on paper, you don't have to think about it

Then, I power through the tasks and mark off the items. It feels really good to check things off!