For me, I just try to make sure I eat enough and drink enough water and that's about it.
The problem with New Year's resolutions - and resolutions to 'get in better shape' in general, which are very amorphous - is that people try to adopt too many behavioral changes at once. It doesn't work. I don't care if you're a world-class CEO - you'll quit.
Providence conceals itself in the details of human affairs, but becomes unveiled in the generalities of history.