You can't only play excessively. You have to play excessively AND analytically. Constantly watching what your opponent does in response to various situations, and reverse engineer ways to beat those responses. You also need to be watching videos of players who are better than you, and looking not just at the obvious macro things they are doing, but at the tiny details. How far they are spacing things, which moves they punish with what, mixups you don't currently utilize. And you have to practice every tech-skill related aspect of your character(s) until you can't possibly **** it up.
It takes hours and hours of constant, daily, thoughtful practice to improve in a meaningful way. You have to want it badly. More than any other things you could be doing with those hours of free time.
All that being said, while I started doing that this past school year.. I haven't been playing much at all since I got home to NJ. Part of why (and why I haven't been posting as much here) is because I've been working hard to get in shape, and be more physically active. (posted about here once or twice before.) Which is going awesome, btw. Last time I had stepped on a scale before leaving school it had said ~170, currently at 151.
And I'm still eating more than everyone else when I go out to eat with people. =P