I never flew with the guy, but a Captain at my previous company used to say "If in doubt, there's no doubt."
I use it to this day and it's along the same idea.
If ever doubt myself, I remember that and it forces me to look at the situation with fresh eyes. It's saved me a couple of times where I ended up adding fuel, planning a different route or altitude, taking the into wind runway even though it results in another 10 minutes...
Of course, it only applies if you are not planning on doing something illegal!
