No matter what you do in your life to get success, FOCUS is indeed your key. Anyone can force themselves to sit in a library and study all day. The hard part is sustaining focus. It matters more than raw effort. The sun can’t burn paper without a lens to concentrate its rays. Similarly, you can burn yourself out working on a project, but if that effort isn’t concentrated, you won’t make any progress. Focus is essential, but it is also incredibly hard to do.
I just wrote a guest post on how to focus here. Please do have a look.