Most people don't do much, if any, work on being rational, and they do 'okay'.

Actually, the word 'okay' itself is a bit misleading here - there's an absolute meaning of the word that means something like 'having access to enough resources to survive', and then there's a personal one - whatever you meant when you said "fulfilling anything like my full potential to help others and/or produce great art", in your case. For the first definition, unless you're in an unusual situation, you should be pretty comfortable assuming that you'll be okay. (Well, assuming you've got whatever ducks you're interested in in a row regarding cryonics.) Regarding the second - wherever you're setting the bar, why are you setting it there? Especially if you think that the bar being in that particular spot makes it unreachable? In fact, why have a bar at all? All you can do is your honest best, and if that doesn't meet your definition of 'okay', I'd say there's something wrong with your definition, not your work, regardless of the specific value of the outcome.