I completely turned my life around starting senior when for some reason I ditched school for a week and studied for the SAT 16 hours a day. I have no recollection of what led me to do that or how my parents allowed that to happen. One of the best decisions in my life. That and my mission completely changed me.
I have a brother and a sister who I would have expected to do incredibly well but now are impoverished due to things that happened after freshman year. I have hope for them but 15-25 years from HS, but I thought they'd be the stars of the family.
One sister who I expected to fall flat on her face turned it around at age 26, another brother at age 33 or so made some big life changes and is doing great.