The difficulty in learning from others mistakes.
I spent my life hearing about how others in my family have done certain things that they wish they had not, actual regrets.
I grew up with the understanding that I would not do those things as they were not what I wanted in life. I knew the kind of life I wanted.
But, as easy as it was to "understand" that I wouldn't make those same mistakes, it was just as easy to actually end up making them.
Looking back, its still difficult for me to understand how I ended up doing the same exact things they did. At times I could even see situations coming. Other times I may have noticed it too late, but realized that I was in it, but still, in both cases, I was unable to get out of it.
Sometimes learning from past mistakes, your own and others, is far more difficult than it seems.