that s how i feel on the set sometimes. so lonely. welcome back. a surprising epidemic affecting some 60 million americans. loneliness. dr. sanjay gupta has teamed up with o magazine. it s called the just say hello campaign. listen to this. when was the last time you said hello to a stranger passing you on the street or a friend you hadn t seen in years? hi. hi. how you doing? hello. oh, hello there. look at you. hey girl. looking good. thanks ellen. oh it s going to come back on me. thanks, ellen. dr. sanjay gupta, hello sanjay. let s start with that.