We are constantly evolving, and can adapt to almost anything if given enough time.
People generally have a habit of creating "comfort zones" in which they eventually become "uncomfortable" leaving (obviously). If they spend too long never really leaving these comfort zones then leaving them becomes beyond simply uncomfortable... it becomes fear inducing and even potentially traumatic.
Comfort Zones are not just places BTW. They are also routines, behaviours, the ways we do things, the routes we take to go places. They are systems we put in place so that we can predict outcomes and minimise unexpected surprises. Spontaneity, whether good or bad do not exist in comfort zones.
I have noticed this in particular regarding the elderly. Completely confident when dealing with the things they know, but they become confused, panicky and even petrified if ever forced to do things outside of their normal routine.
The problem is that given enough time you can adjust so well to "comfort zones" that anything outside of them instantly overwhelms us. We can't "go with the flow" or "roll with the punches". Often we just freeze up and desire to flee back to the "familiar"... to where we feel safe.
But this is not really living. When nothing changes, nothing really can happen. Nothing can stimulate or inspire us. We can't evolve or improve or feel our experiences. Live in the moment. Every day just becomes interchangeable with any other.
A feeling of safety is good... even necessary. But if it can only exist at the expense of everything else required to feel alive. Then it is a heavy price to pay.
Fortunately as I said before. Practising and learning to enjoy things outside of your comfort zone is much easier, once you understand that comfort zones are not necessary just places. And once you re-develop that talent... things outside of them become far less scary again.