Will power, historically the negative of taking the drug usually outweighs the positive, except in extreme cases of course (cancers, stroke, heart disease). It's all about discipline and sacrifice, and once you train yourself to do it; you will be rewarded in other endeavors. The only thing that blocks success is you in the end, no matter the obstacles. Those pills may help in the short term, but they will most likely kill you or hurt you in other ways in the long term.

P.S. I am not a doctor, just married to one. Cheers!