Social life without drinking...?

I'm 16, so obviously I shouldn't be drinking in the first place, but most of my friends do drink and get stoned and all that, and quite honestly that's not my style at all. I've seen firsthand the effects of alcohol and drugs and it's not something I want to get involved with. So, I always tell my friends no when I'm invited to a party because I don't want to stop anyone else from having fun or be a party-pooper haha. But I don't want to keep saying no to my friends and have nothing to do on the weekends. How can I have fun at parties without drinking?