Is it possible to change your own personality over time? For example, a shy person might decide to experience a whole new life by becoming outgoing.

I used to be very self-conscious and shy when I was young. As I got older, I started to use humor to hide my insecurities including self deprecating humor to deflect my shyness. It has helped me greatly over the years.

There are probably things you can change about yourself, but you may not be able to change everything. Good luck.

oh yea it can possible truly depends how much you really trying change yourself within your own

I have been working on this myself. I want to become far more outgoing and see how it feels for a change.

I would think so.
My personality evolved as I matured.