Any regrets you have from childhood? Mine is not taking more notes from the books I'd read

Actually, it's the little things that shape who we are today, and they start building up from our childhood. If we're content with our lives at present, then we're probably happy with the way we grew up, and we don't need to change anything.

Taking the path of least resistance. Example: Taking easier math classes because I didn't think I would need the harder ones in university. In hindsight, the program I would've rather taken required a more difficult math class than the one I had.