Focus. Your gravestone will have the year you were born and the year you died carved into it, but that doesn't matter. This only records the number of years you existed.
What matters is the dash carved between the two dates, which will represent what you did with your life, and how you lived. Do you want your gravestone to read: "Played it safe"? How much time do you think you've got? When will you start living? Why are you waiting? What exactly are you waiting for? Do it. Do it now. Live your life to its fullest.