Hate to burst your bubble, but drinking water, while very good for overall health and comfort while flying, does not protect you against germs, bacteria, virii, etc. Moving your legs and stretching may help protect you against immobility-triggered blood clots but don't do a thing against the bugs. Furthermore, it is not "a" virus, it is a stew of nasty invisible critters. Every human who is sitting on that plane is carrying bugs and by breathing, is spreading them about. Then the air circulation system does the rest.
Wearing a mask is not so far fetched. There is a reason why hospital personnal do this (it protects themselves as well as patients) and there are great similarities between airplanes and hospital wards.
I wear a mask in the house while putting logs in the fire, scooping the kitty litter, cleaning, etc. because I am chemically and environmentally sensitive (allergies) and it really helps. I would feel kind of stupid wearing one on the plane, but I am actually thinking about doing it while this awful virus is circulating. I fly to Panama a lot and that is an international hub that moves people from all over the world. Same for Los Angeles. Right now, the primary vector is China, Taiwan, Vietnam. Think about the connecting flights that your plan will match up with.
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