I am finding a similar principle with wanting to work on my general physical fitness. I had to give up capoeria a while back, because of my work schedule just didn't allow for luxuries like martial arts classes. (There's a real clientelle for 24-hour Nautilus for a reason...) I read some tips for easy weight loss and training in Outside this month, and it was pretty much all stuff I was doing already, sigh. So I figured maybe I could figure a way to schedule better if I took account of my time. Once I started analyzing, I found out I'm already doing more in my available time (I have no "free time") than I have time for doing it, possibly because I'm multitasking. (I can manage to watch 4 hours of TV a week only because I do something else at the same time, like cooking or household chores.) My biggest time-consumers (after living history on weekends, which is a form of workout in itself) are visiting friends and the telephone, which I try to limit, anyway, but you can only defer a certain amount (rather like dishes and laundry), or folks think you're antisocial. Besides, my friends are important to me! But currently, there isn't much room for things like hobbies, workouts, the computer, or other luxuries. Friends who really know me are already astounded at how much I pack into what available time I DO have.
The only time I seem to have is that which I use for sleeping, and I've found that eating into that 8 hours just isn't as easy as it once was.
Still, I've done things like doing kata in the driveway at midnight. Or situps while I'm watching TV. I really need to figure a way to get something like Hermoine's hourglass, where I can create some time out of the ether, though.