The more you concern about your existence the more you trap yourself in the zone where you build it up. I think you just be free living your life and not wondering too much about why you are existing in this world. You know yourself, you know where you are and you know what you should do to your life yet no one else can. Your believe is what you create up so go for what you are trusting and focus on your destiny. Instead of wondering about your existence, do you ever ask yourself about what you do in this world you will receive whatever you deserve in the other world after you die (in Catholicism we called that is heaven and hell).