"Oh man, I wish I'd done ________."
I remember being struck with a particularly insightful quote from Eliezer Yudkowsky. It went something like, "If you're certain you'll have a belief in the future, you should probably adopt that belief now."
The basic idea is that a lot of times we know a particular way we're acting, peer group, set of cultural norms, etc, has worn out and isn't a fit any more. And we know we'll evolve past them and change.
But we haven't done it yet, for whatever reason -- maybe fear, or inertia.
If you can predict yourself in the future, you can think better right now.
Likewise, a fun thought experiment --
Have you ever looked back on a particularly crazy or hectic period of your life, and wish you'd enjoyed it more and relaxed more while it was happening? Or wish you'd saved more money, or taken more risks, or advertised more, or been more generous, or been less generous, or something?
Regrets are useless, but give this a try sometime:
Can you see yourself looking back on where you're at right now and being certain you'd think, "I wish I did more ____________."
Maybe it's relax more, or enjoy what you're doing more. (Probably.) Maybe it's resource-based (save and invest more), or behavior based (follow through more consistently).
Have a think. Do you see yourself ten years from now reminiscing about 2013, and thinking, "Interesting year. X and Y went great. Oh man, though, I wish I'd done _____________."
If yes, you can start doing that right now. And your life stands to be better for it.