One of my favorite internet people, Merlin Mann, had an episode on his Back To Work program where he talked about the idea that you only get so many Saturdays in your life. Saturdays being the days that we usually use to do fun stuff, hobbies, cleaning, things that aren't work. I liked this idea a lot and it got stewing around in my head. Eventually I came up with the idea to visualize this concept of a limited number of Saturdays. To keep the visualization manageable I thought about tracking the number of Saturdays in 10 years. 10 years from now my wife and I be in just past our mid-forties and my kids will either be in college or just out (theoretically). Other than that, who knows?
So as a concrete project, I came up with storing 10 years worth of Saturdays as marbles in a jar. Every Saturday you move a marble into a different jar.