Try flipping a coin, theres meant to be this thing that if you flip a coin and it tells you what you really wanted to choose because if you're disappointed by the coin flip results then you know that you really wanted the other option.
That's the first I've heard of something like that. It sounds reasonable though. Who told you about that?
I mean, typically, I just stop everything, sit down, and figure out what would best lead to my happiness and figure out what's making me doubt stuff, typically over calming music so that I'm in the right state of mind to be making good decisions. But, I'm a thinker (too much so, sometimes). I like rationalizing stuff and working with logic, so I know my methods may not be best for everyone.