Sex, hot shower, reading, slumber. In that order. That usually does the trick.
I have found that if the stresses of civilization become too overbearing, a day spent in the forest does wonders for the soul.
There is something to be said about the exercise of hunter-gatherer instincts in the human well-being equation. Indulging in hiking, foraging, hunting, fishing, and rough camping is very fulfilling to me.
I don't think you're ever quite alive like when you are wrist-deep in an animal's entrails, then cooking that animal on an open fire. Being actively involved in the procurement of a food source is invigorating.
If you eat meat, I highly recommend it.