I had been in the practice of giving blood on a regular basis, right up until I visited one of the countries on the "we don't want your blood" list.  So I'm out of the game for a year.  But shortly before I got disqualified, the blood collection center started a loyalty rewards program where the volume of blood you donated equated to a certain number of points which could be used to buy merchandise through an online store.  I wanted to use up some points before they expired, so I ended up buying a video game (which turned out to be terrible, but that's not the point).  I couldn't help but notice that I quite literally payed for that video game with my own blood.  It seems kind of macabre, but really it was just simple economics:  They need blood; I have blood.  I give blood; I get stuff in return. #health