That's all that Trump was doing. He was visiting some sick and elderly service people. And he was protecting them from diseases he might have, just the way doctors and nurses do in the operating room.
Btw, if you don't trade your mask for a new one every two hours or so, your old mask becomes a haven for all kinds of bacteria and viruses that grow in the mask. Trade it in for a new one, or at least wash it, or you will be infecting a whole lot more people (yourself included) than if you hadn't worn the mask in the first place.
Honestly wearing mask doesn't gives us complete protection then why everyone suggesting to wear one, it better to impose complete PPE rule so there will be no more spreads.
I have been saving a load of money on breath mints, because all those jokers behind the masks can't smell my breath anyway.