If you look at your life like a book there are definitive chapters within it. You're born and chapter one begins. Each chapter is your identity in that phase of your life: who you are, what you believe, what's important to you.
As a youth you are constantly starting new chapters because you're learning and growing everyday. You can't stay a kid forever so you have no choice but to move on. This is the natural way of things: change. Death and rebirth. To grow into a butterfly requires a metamorphosis that closes the chapter of the caterpillar's life. The caterpillar will never be again: death. The butterfly emerges and begins a new life in a new place: rebirth.
But something happens with people once they become adults; many of them halt this process of continuous change. They settle on a static version of themselves and enter into a phase of decay, unbeknownst to them. I don't know exactly what causes this, but I think it's fear of change, which is synonymous with fear of the unknown.
As a kid the changes just happen because the body and mind are actively developing and you just have to roll with the punches and weather the storm. As an adult you must make the changes yourself. You must end your own chapters and begin your next ones. And that means having the courage to step out of old habits and into new ones, the courage to say that's not who I am anymore. Fear of change, fear of judgment, fear of failure, they all weigh heavier on us as we age. The stakes seem higher, the consequences more grave. We are accustomed to things the way they are and we think that's good enough.
How often have you seen people miserable in their jobs, but too paralyzed by fear to do anything about it? They can rationalize all the reasons they stay and convince themselves they're making the right choice, but subconsciously they know it's a lie. They suffer every day and that permeates every aspect of their life. They're stuck in a chapter.
To live fully we must embrace change and accept its inevitability. We must be able to take chances and risks in order to grow. We must accept that fear is a natural part of living, but can't be allowed to dictate the terms of our lives. We must have the courage to start new chapters.