I’ll go first: “You have to have children when you’re young,” told to me when I was in my late 20s, with no desire to ever have kids, and no means to support them, by someone divorced multiple times with at least one adult child who does not speak to them.
Also: Responding to “How do I deal with this problem?” questions with “Oh, don’t worry about it, it’s enough that you’re even thinking about it!”
I have always hated that advice. While exceptions exist, there is no faster way to burn yourself out on something you love than making a career out of it. I generally do like my work (IT) now, but a lot if that is because I actively try to not even look in the direction of a computer when I am not in the office. I probably consume less tech/IT industry news now than I did before I worked in the field.