It's a tough question, no doubt. Have I learned? What was the hardest lesson? Life is a good school, much better school than any academic school can be, but what I found recently the worse it is the better. A happy life without problems (or challenges/opportunities - using the Art of Reframing) teaches us nothing. NOTHING. We are unhappy for a very simple reason - there is no real unhappiness to compare it to. I was no exception - I did not have everything, but I had a financially stable life, unhappy, but secure. I tried to improve, but I was always afraid not to make it on my own. I was afraid to get out of unhappy marriage, I was afraid to dream. Afraid, afraid, afraid. Some people call it being reasonable.
It was all before I lost my ability to be reasonable. I got sick and became insane. My fear and inability to change led me to clinical depression that was treated with antidepressants and it turned out that I was bipolar, meaning that treatment drove me into mania - being high on drugs. It's no fun having no control over your actions, but the lesson - the hardest so far was - there was no way back, only forward - mental hospital, dealing with police, with divorce, financial instability and so forth. But after the turmoil, the biggest thing that I could overcome in my life was FEAR. I saw others not in their best light being afraid and I realized, this is it, it's time to change. In a sense, illness became a blessing. No, it's not easy being me and I will never wish for anyone to have it, but as far as being afraid... Just take my word for it. Don't. Or take the inspiration I wrote on my current diary:
"The whole secret of existence is to have no fear. Never fear what will become of you, depend on no one. Only the moment you reject all help are you freed." Buddha