I agree with posters who stressed the importance of encouraging teens to enjoy their high school experience.
That said, I know that my own experience as someone who attended a top college, as well as my husband’s experience, was that we never worked as hard the whole rest of our lives as we worked in high school. So I did not experience burnout, but rather intellectual rejuvenation, in college.
I thought college (Williams) and grad school (Columbia) were easier than high school because, even though the work itself at Williams was more challenging and intellectually stimulating, it was so much easier to manage your time.
In high school, you are in class all day, then you do your extracurriculars, then you are up late doing homework, and you barely sleep. In college, you attend class for only a couple of hours each day. Suddenly, you have plenty of time to balance your readings and the writing of papers with time to do your extracurriculars and even to socialize. You have time to love learning for its own sake. As long as you have good time management skills, getting your work done in college is more manageable than getting your work done in high school. The work is more challenging, but there is so much more time for it!