My daily routine included going to the gym for a workout before going to work. Every morning I would see my friend Nicholas at the gym. He was seventy-nine years old and in terrific shape. As I greeted Nicholas on this particular day, he noticed I wasn't full of my usual vitality and asked if there was anything wrong. I told him I was feeling anxious about turning thirty. I wondered how I would look back on my life once I reached Nicholas's age, so I asked him, "What was the best time of your life?"