This post, I reckon, is about what to do 'after' stress beats one down, and I'll prescribe a method for dealing with this. However, I'd like to first suggest taking daily "meds" as a preventative measure. "Meds," in this post, is short for "meditation" but the abbreviated term sounds similar to a daily vitamin regime.
Take your meds.
Meditating daily, if only for 5-10 min, is like de-fragging your computer hard drive. If you sit quietly for 5 minutes, I bet, after about 15 seconds your brain will start to offload all of the "stress" that's been worrying you. By meditating daily you are basically emptying your coffers for stress, so when stress happens you have more "room" to deal with it.
A method for dealing with stress, at its worst, would be to find a quiet space, sit or lay down comfortably. Close eyes. Place one hand on chest and one hand on belly below navel. With intention breathe-in filling your lungs entirely but gently. The hand on your belly should move in and out with your breath, but, do ensure the hand on your chest, and your chest itself, does not move. Breathe in for 5 count, pause for 2-3, breathe out for 5.(It will take about a minute for your breath to relax, don't push it) Do this breath cycle for as long as you can. This also can be used if you are unable to fall asleep.
There is a nerve that runs along the backside of your stomach all the way to your brain. When you stimulate this nerve it precipitates Serotonin to be released in your brain, among other neurotransmitters associated with mood. You have already experienced this feeling after eating a large meal and noticing how tired or sluggish you get afterwards. The stomach starts moving around, digesting food, stimulating the Vagus nerve, making you tired. The breath cycle above will do the same thing.
Take your meds!