My husband's been on Oxygen since May. He's on 3 liters 24 hours. His physical therapist just suggested that she will ask dr. to increase to 4 liters when he's exercising.My husband's 44, and yep, everyone stares, asks what's wrong, he's so young, etc. He's been so totally awesome about it. Just looks them straight in the eye and answers, like it's no big deal. I know it makes him feel very weak and uncomfortable, but he does everything, just like he used to. He runs the tube up his shirt, so it's only visible on his face (I wouldn't care if it was visible, that's his thing.) He also puts the portable unit in a back pack. Makes it easier to carry, less noticeable. Of course, I don't know how good it is for the unit, but that's what he needs to do to make the situation acceptable for him. And he always has to tell stores, etc., why he's carrying a back pack so they don't think he's a shoplifter or carrying a bomb or something.He couldn't live without it, so I'm thankful for it. Good luck to everyone. Jan