You can accomplish a surprising amount in fifteen minutes. For example, you can read a chapter in a book. You can meditate. You can break up what you're working on into a fifteen minute block, although I would leave my work for the extended periods of the day set aside for working. So I'm talking about the fifteen minutes for the other stuff. Wash the dishes. Pick up your room. Do the laundry. Vaccuum. I'm sure I don't vaccuum nearly enough.
How many fifteen minutes do you have a day? I would guess between eight to ten. You need to leave out sleep, work, and time to goof off. Those three things are just as important, even if some are more fun than the others. I would think you have two or three hours left over that you can do to keep your life sane, to keep your life organized, and to keep your life meaningful and happy.
Do you have a project you're working on? Maybe something you built over a few weekends. You can't just let it sit after that. You need to keep it going, or maybe start work on another one. To keep your momentum up on that special skill, to keep up your motivation to work on something else. Fifteen minutes a day to look it over, play with it, polish it, talk to it, whatever, will do the trick. Just try not to skip a day. Who knows, you might find yourself so absorbed in it you go way over the fifteen (which is almost always a good thing), for these kinds of fifteen minutes. I'm sure you'll be able to find other areas to cut down. For example, TV is great sometimes, but it can be a dangerous time sink. Hanging out with friends might be the best thing in the world, but don't be afraid to be by yourself sometimes. Figure out how to deal with your email faster. Figure out how to do your job faster. (Don't skimp on sleep.)
Fifteen minutes doesn't have to be fifteen. It can be twenty, twenty-five. Probably not more than thirty. But I like these short condensed periods of times to do a small thing. It's like a little deadline. Remember when you had a paper due the next day, and how much faster you worked compared to the previous week of working on it (if you did at all, of course). Put a little pressure on yourself. I can't imagine washing dishes would ever take longer than twenty, but it gets pretty bad if I get lazy about it. Choose your fifteen minute things and squeeze those fifteen, push yourself, so you can do more fifteen minute things.
Here's a good strategy. List out the things you think will take you fifteen minutes that are probably good for you to do. Then every day, do one or two of them. See if they really do take fifteen minutes. See what it feels like to do two things you've been procrastinating on in practically no time. Now do more of them. If you're doing four or five each day, that could be more than enough for forever, to keep your life clean and meaningful.