Omega-3 fatty acids. DHA and EPA act as anti-depressants. Eat lots of salmon, herring, tuna, etc. or if you don't like fish, ground flaxseed you can stir into milkshakes, plus some margarines and eggs have Omega-3's in them. Eat 5 small meals divided into regular intervals during the day. Keeps your blood sugar from spiking too high and prevents you from the subsequent crash and feeling crappy/lethargic.