So I'm regularly doing 60 flights of steps per day and have now stepped up my training by adding a weighted backpack. It's only my developer rig and a litre of water but it makes a big difference. I'm doing this because on the everest trek my legs and feet were fine but my back was in agony so I thought it might be wise to build up my back muscles this time. Ideally I should work my way up to 100 flights and 20 lb. of weight but I don't see how I can do that at work without looking utterly ridiculous.