I too graduated just a few years ago, so one thing I can recommend in addition to the wonderful suggestions above is to make use of your free or heavily discounted campus gym membership. That is one cost you don't have to deal with right now, so it is the best time to make gym time a habit.
You might say you don't have time to go to the gym, but if you honestly try to make time you will realize just how much time you previously thought you spent studying, but were actually spending on FB/Youtube/Wikipedia, etc. Trust me, I've been there
1) eat real food - more vegetables, moderate meat, moderate fruits, less grains, less sugar, less vegetable oils.
2) exercise - moderate intensity cardio, sprinting, heavy lifting, dedicated stretching and mobility.
3) live - relax, de-stress, meditate.
Disclaimer: I'm not professionally qualified to make any formal recommendations. I've just done my homework and I'm my own guinea pig. All of my data, unless otherwise cited, comes from a sample size of n=1 (me).