It takes a while to figure out what works, and what is important, for me as I'm getting older I have less energy, or ability to cope, whereas in my 20's I would happily be out very, late and very drunk (UK based) and still be able to do some semblance of work/life. As it happened I really like to smoke, however unacceptable for my GF.
Now, ten years on, it is important for me to get through the work week in a better shape than I started it. That means slightly more healthy, and progressing in my work. Having your day task list ready at 6am, means during the day I know exactly what I want to acheive, and am just trying to tick off as many as possible. (I use Getting Things Done (GTD) for that.), and going to the gym gets me slightly more healthy.
I do these things first in the day, before something knocks my schedule off, hence getting up early, that way I know I am much more likely to get my stuff done.