I've found that the things I procrastinate most are things that have high "activation energy", for lack of a better term. Getting off my computer, getting to my car, and driving to the gym takes a lot of up front willpower, even if I find the actual working out enjoyable (or at least tolerable). The approach that I take to resembling a functional adult is to make small adjustments to my routine that significantly cut down on that activation energy. To use the gym example, I started showering at the gym. Every day, after work I go to the gym to shower. Some days I don't have the energy or time to work out, but I always show up, grab my gym bag from my car, go to the locker room, and shower.

That way, it's not a question of "do I have the energy today to go to the gym and workout?", it's just "do I have the energy today to workout while I'm at the gym anyway?", which is a much lower bar.