Courage is not certainty; certainty rarely requires courage.

When you are sure, acting takes nothing. It is precisely the absence of certainty that gives courage something to do, which means the discomfort of not knowing is not an obstacle to bravery but its raw material. Waiting to be sure is waiting for a state in which the quality would no longer be needed.

If you have been telling yourself you will act once you are certain, notice that the condition is unmeetable. Ask instead what level of confidence would be reasonable for a decision of this size, and whether you have already reached it. Most of the time you have, and what remains is not doubt but nerve.