I did pretty well in high school ... if you count grades as an indicator. I had an A/B average and a 4.0 my senior year. Of course, it was a lowest-common-denominator school in the Rio Grade Valley ... and I would find out just how little I had learned when I attended college on the East Coast.
Bottom 10% of my class at West Point my freshman year. Almost failed out. In those days you could fail only one class if you were not minority or female ... not a value judgement, but fact. I failed my one class and then barely made it through sophomore year. Then something clicked. I probably caught up learning all the basics that I did not learn at my poor high school. Managed to make deans list my last 2 years and graduated in the top third ... albeit with only a 2.89 average overall.
Grad school was a lot of fun, and I enjoyed classes immensely. I took my time (3 years) and came away from it with at summa cum laude with a 4.0 average. Not sure I could do it again. It was the right time and place. I take too many medications now that drain my energy and cloud my mind.