For me it really goes with stress. When things are running smoothly and I have a decent amount of free time, I sleep well, eat healthily, and work out regularly. When things are busy, and I have a huge to-do list, my stress level is way up, and there's tons of stuff demanding my time, I sleep less and poorly, I crave carb and fat rich foods when I'm stressed, and I have a much harder time taking breaks to workout, etc...

Right now I'm dealing with my first house purchase and a cross-country move on top of my normal work, and my health has taken a big dive. Hopefully once I move and things settle down, I'll get back on track.