Recently I was listening to one of my favorite podcasts, Invisibilia.  It's also a show on NPR.  It's about all those things in life that can't be measured.  The things that aren't physical. 
The episode was about the idea of "personality" and how we perceive it, both in ourselves and in others. 
Apparently the consensus for most of our history has been that our personalities don't change over time.  That ultimately, "we are who we are" and nothing can really change that. 
This is apparent when we think of criminals.  Once a rapist, always a rapist.  Right? 
Turns out this might not be as true as we think. 
Someone did a study and determined that how we react to things is much more based on our situation than on our "personality".  Anyone is capable of anything, given the right set of circumstances. 
In addition, our perspectives and ideas also color how we see the world and therefore how we react to it. 
One of the hosts said that the idea that anyone could do anything, and that there is no way to really know someone based on their behavior historically, is terrifying.  How can you ever get married, knowing that the person you are marrying could turn out any kind of way in the future? 
I don't find it terrifying though. 
I find it freeing. 
This means that we can choose to be anything we want.  We are not trapped by our personality. 
This gives me hope that I can change.  That I can make my life better. 
I can be anything I want.