To conquer doubt, we must act as if there is no doubt. Doubts are stong and persistent. Follow your goals with action. Act as if you have no doubts. That action will eliminate the doubt, and, as it happens, lead to the fulfillment of your goals.
Action is the key that conquers doubt, and turns dreams into reality.
Start walking, and you'll know, without a doubt, that the journey is possible. Because it has just become so.