If we wait until the fear is gone, then the opportunity will pass. If we wait until we are sure that we will get perfection, then we will never start.
The time to act is when we have intentions. Time to act as soon as we feel the urge to make a difference.
If we are in doubt, then we will start talking to ourselves to get out of there. When we give in to doubts, then those doubts will usurp momentum from us.
Let fear tell and prepare us, but do not assume that it should stop us. Realize, that anything we doubt can do is exactly what we have to find a way to do it.