That's a good rule. The thinking never ends. I also try to convince myself that discomfort with an idea is a reason to do it rather than avoid it. So ... what about the other rules?
The first is "don't get hurt." It started when I started running again, taking the time to slow down and practice good form and worry less about how fast I was running. That made a big difference, and my early years of joint pain are gone. It's become even more important as I venture into backcountry hiking. It reminds me to take the time to do it right. And when done right, I can do the things I dream of. Number three is a bit more lighthearted: "always go see Broken Social Scene in Toronto." I know you aren't as into live music, but I've seen BSS in Toronto four times, and all four were superb. It's a great time and a good city, and the band always nails the hometown shows. If you're ever looking for an excuse to travel there, seeing an increasingly rare BSS show there is a good reason.