Failure; it is one of the best lessons I have had in life, both as a person and as a leader. Failure can cripple a person, if they don't explore the failure, dissect the reason behind it and look for the valuable lesson in it. Near failure is also a great lesson as well. Don't beat yourself up. We all fail. Challenge yourself to use the failure to change yourself or your actions.
Here's a story of one of my biggest near failures. When I was in the Navy, I had a Sailor come to me in the middle of the day asking to talk to me. It was a crazy day where I was coming up to a deadline for a major report that I needed to turn into my Commanding Officer. For a split second, I thought of asking them to come back later. Luckily, something made me stop and take the time to talk to them. They told me that they had bought a gun the night before and that they were planning on taking their own life that day after work. What was my near failure? I almost put my own needs and priorities in front of one of my people's. What if I had not stopped to talk with them? The lesson for me: always be there for your people. Always put their needs before your own.
As for what I would do if I knew I could not fail? I would remove the hatred in the world. Every day we see people turning their backs on others, usually of their own selfish accord. There is far too much hate in the world. If I knew I would not fail, I would do something so that we all only saw the good in others, and would ensure that we all love one another.