Anyone work in an office??

Normally I don't mind my job because I don't have to do hard physical work but now that I'm pregnant, I'm so nauseous and tired. Sitting here all day seems to make it worse.  I can't really walk around bc our building has a lot of security to go in and out of, I can only go out during lunch which I normally don't do bc I only get a half hour so I use it to eat lol. Anyone else in the same boat? What do you do to stay awake and get through the day??