What is your biggest regret/one thing that if you could, you would do differently?

I am curious and hope to gain some great insight in reading of people’s lessons;biggest regrets or the ‘one thing’ they wish they had a chance to do differently. Also, if you are brave, provide your relative age bracket, it may have a huge impact on another.
My biggest regret was not staying in college at 19. My parents were willing to pay for everything if I lived at home while attending the local Jr. College. I was on the dean’s list both semesters I attended, but I was a rebellious daughter. I moved out of my parents house so I could do what I pleased (stay out all night, etc.) I intended on getting a swing shift job and going back to school, but dang it’s hard to go back when life gets in the way. Here I am, in my 50s and back pursuing a degree to have a 2nd career. I’ve been blessed, my first career has been a 30+ year employment several promotions and a good life….but, I see more options will be open for me if I have that certificate. And I still enjoy college, even after working all day and overseeing my household of spouse and 3 college-age sons.