In this case around blood donation. i sat down with sheryl sandberg, she doesn't do a lot of interviews, i have to tell you she was surprisingly personally sort of passionate, john, about this topic. >> when you think about donating blood, you probably think about disasters, mass shootings, tornadoes, utter devastation. >> the irony is the patients who suffer from those tragedies actually they are alive because people days before had given blood to make sure that it's readily available. >> as a doctor at a level one trauma center i've seen the extraordinary demand. in fact, every two seconds i...