Any regrets in your life? (Especially for the older people here).

I am 76 years old now. I have started having massive regrets about my major decisions and paths taken in my life. I now believe I would make entirely different decisions in my life if I were to do it all over again. I had some very difficult challenges in my life and I tried to do what would help me overcome problems as best I could. Now, with a lot more knowledge about my situation, I can see I needed a much more sophisticated and complex plan for overcoming the problems I was having. (For the grim and bizarre details, you can read my Featured story here). I know I did the best I could and by popular standards I didn't do that badly (I'm a retired teacher who mostly taught kids, then later adults, in locked facilities). I have few friends but they are long term good friends. Things could certainly be worse. However, I know now I would have built an entirely different life if I had it to do over again.