It’s pretty much about stretching yourself but not overstretching. The classics might be the latter for a teenager. I guess it depends on the person.
It depends strongly on the person. Blessed are those who have/had a teacher that could recommend them the right books for them at any given time. I didn't start reading for leisure again until my late twenties when The Hitchhiker's Guide to the Galaxy drew me in, despite growing up reading everything from Franco-Belgian comics to Karl May.
High school kills any interest in reading more often than not.
High school kills any interest in reading more often than not.