If you study too much you have no time for movie/fun/shopping and other enjoying activities, you will also get your eyes spoiled.
If one reads a lot then his expectation from exam will be high comparing to the student who is not studying at all.
Getting 95% is sometimes not satisfactory to a guy who is a book worm and he feel sad while if a guy who never study got passed by just 36% throws a party to his friends/village.
so you can understand who is living happy life at from starting to last.
Do not wait to strike till the iron is hot; but make it hot by striking....