Doubt

Those who doubt your ability probably have a valid reason.

When in doubt chicken out. – Robin Jones Gun

It’s better to keep your mouth shut and appear stupid than open it and remove all doubt. – Mark Twain

When in doubt, remember “FISH”: Fuck It, Shit Happens.

The problem with the world is that the intelligent people are full of doubts, while the stupid ones are full of confidence. – Charles Bukowsky