the reservoir of all possible opportunities still available to you at this point in your life—all the countries you still have the energy to explore, the careers you still have the courage to pursue, the skills you still have time to develop, the relationships you still have the heart to make—like a pail of water you carry around in your head, which starts off feeling like an overwhelming burden but steadily draws down as you get older, splashing gallons over the side every time you take a step.