Innovative/constructive question

So I'm trying something here. Since people are sharing their opinions I thought it could be interesting to share an opinion you used to have. Like you changed your mind because you realized your opinion is harmful, inaccurate, biased or just you were convinced by the opposite opinion etc.
I'm feel like I'm not very clear so I'll give an example.

I used to think that depression was like being in a bad mood. Like you could work on it by cheering yourself up and making efforts to view things positively. I thought it was very easy not to feel depressed anymore and I couldn't understand why people don't do what seemed to me as a small effort to feel better. Then, I talked to my friends, looked up on the Internet and got that I was wrong and depression is something more complex that just being in a bad mood.

PS: No bashing obviously. The goal of my question is to show that opinions change and sometimes opinions are biased because we don't know enough for example or we were educated in a certain way. This is not a court or a confessional where you have to confess crimes or anything.