Better to Give Than Receive? Whatever.

How is it that our company can offer a free financial education seminar, and we quickly get 123 people to sign up in one day, yet we can't get even half that turnout for charity events? Over 300 ppl signed up for cheap flu shots, why don't we have 300 donors at our blood drive?

I know the answer, because I'm guilty of it as well...but how can you tap into that energy in order to channel it into more worthwhile causes, other than one's own money?