There's a difference between getting older and growing up. Both are a process, but growth requires the ability to be introspective, self-evaluate, and strive for self-improvement - not easy things for people to do.
As a career and life coach, I spend a great deal of time talking to clients, students, and those that I mentor about growth to facilitate that process.
Over the years I've identified 5 primary reasons why people don't grow.
1. Lack of self-awareneness