Show me a human that has no fear. It is said most of our motivation in life is based out of fear. I heard a wise yogi say once we are motivated by three things: Fear, hunger & having to go the bathroom.
It's the time of the year that my students start practice teaching and inevitably I get lots of phone calls, which I am actually grateful for. I believe in fear we also have humility. To this day I get butterflies when I teach. That is right after 7000 hours or 12 yrs of teaching yoga I still get nervous.
How can be expect that we will ever gain anything in our life if we don't step through our fear and try something new. The hardest thing for many in trying yoga is walking in the door the first time. Once you have the big picture break it down into small steps, then take the first one. You will be scared and you will make mistakes and with time you will be so proud of yourself and have a great sense of accomplishment.