If you are really struggling with happiness, maybe talk to your dr. about antidepressants. The pain is real. Take something to manage it.
Did that all through college. I may have been on too strong of a dosage, because all it did was make me want to sleep and demotivate me. I don't believe in anti-depressants, especially when the cause of the sadness is something wrong in your life. It was very painful withdrawing from that drug. It took me a year and a half to get off of it, using a liquid form that I could easily taper. Instead, I believe in eating right, exercising, socialization/family/support, and pursuing things that make you happy while avoiding things that make you sad.