I've learnt that I can be disciplined. I used to be flippant. But I've learnt that given a goal I'm invested in I can get very disciplined and that has been a very pleasantly surprising thing I've learnt about myself. Building a financial kitty, running a business and taking on more familial responsibility as our parents age has been possible only because I've become more disciplined about what expectations I set for myself and what I want.
I never thought I'd enjoy this. And my 20 year old self would either be very impressed or find me very boring