9 Ways Twentysomethings Screw Up Their Lives

30 is not the new 20. 80% of life's most defining decisions are made by age 35. 70% of lifetime wage growth happens in the first ten years of a career. More than half of Americans are married, or are dating or living with their future partner by age 30. The brain caps off its last growth spurt in our 20s. Personality changes more in our 20s than any time before or after.

As a clinical psychologist who specializes in twentysomethings, I've spent more than 10 years listening to the behind-closed-doors stories of hundreds of twentysomething women and men. In The Defining Decade: Why Your Twenties Matter--and How to Make the Most of Them Now [Twelve, 22.99], I share what psychologists, sociologists, economists, neurologists, human resources executives, and fertility specialists know about the unique power of our 20s and how they define our lives. Your 20s are a time when the things you do--and the things you don't do--will have an enormous effect across years and even generations to come. Here are 9 things that so many twentysomethings do that mess up their lives:

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