Productive people have as much fear as anyone else in life, I believe. But their relationship to fear is different. productive people can be afraid of heights, planes, all sorts of things. But for a highly productive person, the biggest fear in life is the fear of not trying something of having a regret of Oh, I wish I had made that painting or I wish I had written that novel or I wish I had started that software company. That is the biggest fear, highly productive people. It's not the fear of failure because failure can be overcome.
Failure can be used as experienced to help you for the next success. If you never start something, and it's the end of your life, you're out of luck, then that's the ultimate fear of productive people.