Time
Time moves a lot quicker these days, it seems. When I was in high school, a friend (who was about the age I am now) pointed out that when you're younger, a week is much longer in relation to your life than it is when you get older. I can relate to that now, since weeks seem to fly by a lot quicker than they did back then.
On one hand, I still have plenty of ideas and projects I want to attack. Things for the house, life goals, and projects, electrical, musical, etc., that I want to attack. It's actually still quite easy for me to think of things to put on the mental queue. On the other hand, after a long work day, it's nice to just settle down after dinner and watch Star Trek with a cat on one's lap. I fit chores in here and there, and work on little things, but when in that state it's hard to think about the loftier goals.
Finishing something, getting some kind of milestone, keeps me going. Even if it's nothing huge, just getting some kind of finished product is a great motivator. And at least I can say I made it part of the way.
Find me at @toroidalcore@hackers.town