Fear

"What are you putting off out of fear? Usually, what we most fear doing is what we most need to do. That phone call, that conversation, whatever the action might be – it is fear of unknown outcomes that prevents us from doing what we need to do. Define worst case, accept it, and do it. I’ll repeat something you might consider tattooing on your forehead: What we fear doing most is usually what we most need to do. As I have heard said, a person’s success in life can usually be measured by the number of uncomfortable conversations he or she is willing to have. Resolve to do one thing every day that you fear. I got into this habit by attempting to contact celebrities and famous business people for advice"

Timothy Ferris, from the book The 4-Hour Workweek.