Not (very) applicable if you have a strong gender identity
I think this one is also applicable if you do. Anyone who feels the need to do certain things, or avoid other things, against their actual wishes in the matter, because their "gender identity" tells them, "a Man must ---" or "a Woman must ---" would help themselves by learning this lesson.
Many people find it helpful to have a clearly defined gender persona, however. It's just that people who have a strong pre-existing preference in the matter (which is essentially what a "gender identity" is) will probably choose to project an outward persona that's consistent with their preference.
Sometimes our minds suddenly "click" and we see a topic in a new light. Or sometimes we think we understand an idea, think it's stupid and ignore attempts to explain it ("yeah, I already know that"), until we suddenly realize that our understanding was wrong.
This kind of insight is supposedly hard to transmit, but it might be worth a try!
So, what kind of important and valuable insights do you wish you had earlier? Could you try to explain briefly what led to the insight, in a way that might help others get it?