This is all you have. This is not a dry run. This is your life. If you want to fritter it away with your fears, then you will fritter it away, but you won't get it back later.
I've accepted the fact that there's a beginning and end to everything. All species are born, evolve, and then die off. We're going through the 6th great extinction and the large mammals are going first and, you know what - we're large mammals!