Failure is enriching. It's also important to accept that you'll make mistakes - it's how you build your expertise. The trick is to learn a positive lesson from all of life's negative moments.
The trouble with Christianity is, not that its failed, but that it's never been tried . . . not that it can't remake the world, but that it's difficult.
Man gives every reason for his conduct save one, every excuse for his crimes save one, every plea for his safety save one; and that one is his cowardice