Yikes... Dartmouth College did a study looking at about 8 million people over the last 3 decades... why? To find out when we're most miserable.
The answer is... 47.2 years old.
We start happy at 18, getting more miserable until we're 47.2, but then guess what! We start to get happy again, and when you turn 70 you'll be just as happy as you were at 18!