How can i be happy without drugs?

i am so dependant on weed that now when ive (been trying) to stop to p a drug test for school, i feel like so much **** everyday, i have dont things like vicodin and i quit that before i got too hooked on it, but i have a sleep drug seroquel that i almost OD on everyday to get very high and sleep for as long as possible. at about 3:00 because by that time i just want the day to end, so i sleep for about 2 1/2 days and i wake up and just want the day to end again. how can i be happy without any drugs, at least until i p my drug test (seems like its forever away but if i smoke again ill fail it, and i really needa get into that school. I used to huff before i smoked weed but now when im out of it i huff constantly. help please, thank you