Not all of us have room in our wallet to donate to charity, or room in our schedule to volunteer weekly. Most of us will never find ourselves in that perfect place at the perfect time to be on the hero end of a heroic rescue. But there's one thing we all have in equal abundance: blood. And every two seconds, somebody needs some. It takes just an hour to donate, and though it's abstract to think about, it can literally save a life—at least one. Not to mention the free juice and cookies.