Augustin Kennedy's answer is incredibly thought provoking — I encourage you to click through and read his entire response.
Really think about what success means to you, because I can promise you that “success” — even professional success — doesn’t look anything like how the media portrays it. It is truly a state of mind.
Reading a statement like this is difficult for me; I have a very hard time separating personal success from professional success. Many of my peers would describe me as a "workaholic," but I've learned that setting aside time for yourself (with a hobby or side project) leads to a more balanced career.
Personally, I've been doing CrossFit 3-5 days/week for the last four years, and you'll never see me go a weekend without working on some sort of side project. Some will argue that I take on more than I should, but I find that by keeping myself busy, the feelings of "emptiness and hopelessness" described in Kennedy's response haven’t settled in. Focusing on improving yourself mentally and physically always seem to lead to success. This sounds kitschy, but the reason you see this sentiment parroted throughout the internet is because it's true.