Dale Carnegie – Inaction breeds doubt and fear. Action breeds confidence and courage.

Inaction breeds doubt and fear. Action breeds confidence and courage. If you want to conquer fear, do not sit home and think about it. Go out and get busy

Dale Carnegie

This quote by Dale Carnegie reminds me of another quote concerning inaction vs action:
Whatever you can do or dream you can, begin it. Boldness has genius, power, and magic in it. – Johann Wolfgang von Goethe

This might be one of the key points that distinguish successful entrepreneurs from others, taking action.
Taking action sets you on a a road, that evolves with time. It also gives you the courage to pursue the idea, now that the first step barrier have been breached. In a sense taking action grants you the confidence in your project and the courage to pursue it.

Inaction, on the other hand, create hesitation, doubts, fear of failure, inaction is the number one reason people and entrepreneurs fail.
I have known a lot of people that eventually gave up on their ideas and projects because they waited too long to take any action.
When you do not take action, you start having doubts. Doubts kills risk taking behavior.