When the weather is perfect for riding when you are sitting in school, but when you finish at the end of the day and can finally ride the weather is crappy.
Also people that don't think mountain biking is a sport.
crashing/not being able to sleep/constant rain/running out of weed.
Ha ha, I was in that place until july last year when I kicked the weed for good. It's great not having to waste money on that shit and stress out when you cant get hold of your dealer. Weed's alright if you can moderate and only use it a few times a year but for most it becomes an addiction.
Infrequent use means it's relatively harmless, but if you smoke it everyday, or most days of the month, you're harming yourself. The smoke is obviously harmful, but THC, when used too much has been show to damage the central nervous system, which just generally retards you. I think you know you have a problem when it becomes something you do (or at least crave to do) everyday, even alone.