At the end of the remarkable rock climbing film The Dawn Wall, pro-climber Tommy Caldwell, described what it was like planning his legendary free climb of the Dawn Wall of El Capitan (my rough paraphrase):
“For ten years I mapped out what I hoped was a climbable route up the Dawn Wall, never really sure that it was possible. It was ten years of failure — dead ends, big falls, hurting myself. But I was committed to my goal: free climbing the Dawn Wall.
“If you are going to attempt something, you might as well dream big. You will spend most of that time failing. But you will have at least accomplished more than if you had a more modest goal.”