"Midlife crisis begins sometime in your 40s, when you look at your life and think, Is this all?"

Other than the fact my midlife crisis started about age 17 or so, it's good to know I'll pull out of the curve before I die.  

 The Impact of Age on Happiness, Especially In Times of Crisis : The Art of Non-Conformity: "New research reveals that situational happiness or sadness may relate partly to age. From Jonathan Rauch in The Atlantic — “Long ago, when I was 30 and he was 66, the late Donald Richie, the greatest writer I have known, told me: ‘Midlife crisis begins sometime in your 40s, when you look at your life and think, Is this all? And it ends about 10 years later, when you look at your life again and think, Actually, this is pretty good.’"