For one floor up I take the stairs unless I'm carrying something awkward. For two flights up I will almost always choose the lift because stairs make my back hurt and unless I run up them, I will arrive wincing and unable to concentrate. For down I will always choose the stairs unless they are the stairs in the main building at work that go round a big empty central light well and have glass screens between the stairs and the banister rail, because going down them makes me dizzy. I have been practising going down those stairs and determinedly looking away from the well though because I don't want to hold everybody up being vertiginous if there is a fire.