...didn't make sense not to live for fun
your brain gets smart but your head gets dumb...
(All Star - Smash Mouth)

working hard and having fun should be in an equal relation ;)
and not just the fake fun!! but the real fun...!!!
where you can smile and laugh with your heart...
so one question if you're working hard right now: Are you having fun??
I don't think so... ;) so take a break for awhile... go outside and do something fun!!!
be back in an hour and you'd be smarter than before ;)