Don't change

When I was young (grade 7-grade 12), the number one piece of advice people gave me was: "don't change". I have many memories of this… when one of my friends was moving away, she wrote down for me her new contact information, and underneath it she wrote "you're so sweet, don't ever change". My grade 7 Tech Ed teacher (I will never forget this) called me up to his desk on day while everyone else was working and told me not to change. He said that when I grew up people would get mad and be rude and mean, but that I shouldn't change for them or because of them. At the time, I was completely confused by what he was saying. I kind of still am, but I think I understand him a bit more. Over the years I have encountered difficult people and been tempted to be a nasty person just because so many people these days are, and they tend to get what they want, too. But the voices of the dozens of people who have told me not to change have been in the back of my head.
And every time I think about that advice, I question it: how can they tell me not to change? Change is inevitable, especially when you're growing up. I am a very different person now than when I was 13. Goodness, I'm a very different person now than when I was 19, or even 21! I'd like to think that I am still a kind person, but that doesn't mean I haven't changed. I'm a more efficient worker, I'm more organized, more confident, more willing to stick up for myself, more decisive, more independent, less concerned about what other people think about me, less naïve, less willing to put up with other people's crap and bullying, less inclined to accept unfair treatment… in general, I am a much stronger person, but I wouldn't say I'm ruthless. Sometimes I wonder if I would be even more different now if I hadn't had so many voices inside my head telling me not to change. Would I have become completely selfish, caring only for myself? Would I have become a mean person in reaction to all the mean people I've encountered?
I wonder about it a lot. Most of the people who told me not to change are no longer in my life (I wouldn't even know how to track them down) but I still feel like I owe them an explanation… I wonder what they really meant when they said that. I wonder if they feel I have followed their advice or not (not that I would revert to my old self if they didn't approve). They probably have no idea how profoundly their little comments affected me. I often wish I could meet them again and show them what I've become.
"Change is inevitable. Growth is optional."
No one can dispute the fact that I have changed a lot over the past 10 years, but I've always endeavored to keep the best parts of my personality. I'm happy with how I've grown as a person.