I had a similar experience through grad school, and have felt perpetual burnout for the last 10 years. There's no right answer, but I recommend looking at the writing of Mr. Money Mustache and other FIRE (Financially Independent/Retire Early) literature (e.g., JL Collins, etc...) and pushing to save and invest as much as you can. I take great pleasure knowing that now, after about 10 years of work, I won't have to work another day in an office again.

Also, be sure to exercise :).