I started donating in my late 20's, after several friends had talked about their own donating experiences and reasons for doing it. Most had a friend or family member who needed it. I didn't know anyone at the time who had received any, but I started anyway. I got away from it for a while, then back in, then away again.
A few years back my dad got cancer, and wound up needing transfusions. It was my call to return to the donation center again. He wasn't the same type, he was A+, I'm A-, but someone out there was helping keep my dad alive, I kinda felt I should be returning the favour. I had to pause again for a bit, but just did my 35th donation, with my girlfriend who did her first. She's the 8th person I've recruited to do at least one donation with me.