It can be things like:
Health, mental health Issues
Relationship issues
Family Issues
Too much sports
Too much partying/Clubs/videogames?
Working too many hours
Feeling like what happens if you try your best but still don’t do well?
Too much freedom
Executive function issues
Not prepared from your HS classes
First time going to college
Big fish in your HS, but now a small fish and you don’t want ask for help because you have always been the “smart one”.
Taking courses that you just cannot succeed in
Also for HS, your parents and teachers and school are supporting you and making sure you attend and do your work.
At college you are very much on your own to do these things