What would you attempt if you knew you couldn't fail?
If you were 100% certain it would work, what would you invest your time and effort doing?
The answer to this question is your life purpose. It is what you should be spending your limited time on this earth pursuing. Everything else is a waste of your unique ability to bring value into this world.
Nothing is certain. Failure is an option, but it is an option you need to take.
Do us all a favor and take the risk of failing. Take the step of vulnerability. Only when you allow yourself to be vulnerable do you open yourself up to the possibility of being truly at peace.