when i got nothing to do, I would open the book and spend 2 or 3 hours trying to solve some equations :)

Reminds me with the student who write at the bottom of each page of the answers page, to be continued ... until the teacher reach the last page and found this message ... What are you looking for exactly?

Do not dwell in the past, do not dream of the future, concentrate the mind on the present moment. (Gautama Buddha)