What are humans most afraid of? Failure.
When you think of fear, you think of the very thing that keeps us from moving forward. Fear is the "Satin" of your conscience. It taunts you, keeping you from succeeding your purpose.
I would sit sometimes, think of all the things I'm afraid of, and go over all the things I've let fear control. You'd be surprised how much fear dictate our decisions sometimes.
I heard probably the REALEST quote ever: If we let fear drive our decisions, we will never experience true joy."
It's okay to be cautious, just don't let your fears run your life.