I'm usually not big on "quick fix" techniques, but he
re's one that works well. If you're in the middle of a tough situation and find yourself spinning into a morass of negativity, tune into your thinking. You'll probably notice how specific your thinking about the situation is. It might sound something like, "I can't believe my boss laid that project on me so late in the day. I've already got two extra tasks to get done before I go home, and Mike's been waiting for the report I promised him." And so on. And the further you get into the weeds of whatever is going on, the worse you feel.
So if you're feeling frustrated, angry, down in the dumps, or just plain overwhelmed, try focusing on something pleasant, that's happening right now - and try to keep your thinking as general as you can. For instance, stop and look out the window; notice how pretty the tree across the street is as its leaves are turning colors. Then notice how your mood has shifted to the positive. Once you're in that more positive place, try to stay there for a minute or so. You'll probably notice that the stuff that was dragging you down a minute ago seems less bad, and you might even have a bit more energy to devote to the task at hand.
So in brief, if you find yourself getting "negative and specific", 
try a quick shift to "positive and general". It'll boost your resilience almost ever time.
Let me know if it works for you!
Best,
Dean Becker