Using the stairs is generally considered better exercise than using the lift because the latter are powered and the former not (unless they're moving stairs). This could be remedied by making the lift pedal powered.
The lift is small and light, just big enough to hold one adult in a seated position. It contains a bike saddle and pedals, and a button on the wall. On entry, the passenger has to opt to switch it to powered. The default operating mode of the lift is for it to be powered by a ratcheted and therefore safe pair of wheels. There are two gears, upwards and downwards. To operate the lift, the passenger pedals until they have reached the floor desired. On the way up, they are lift their own weight using their legs on the pedals, which would probably be more strenuous than using the stairs (don't know why i think this but i do). On the way down, they are acting against the counterweight on the other end of the winch.
Because the lift is small, other potential passengers are encouraged to use the stairs anyway because otherwise they must queue.
Also saves electricity.-- nineteenthly, Jul 28 2011 Human-powered elevator http://www.core77.c...allenge/humanpower/ [Klaatu, Jul 28 2011] I like the 3rd image in your link, [Klaatu]. Two women, standing in curvy poses, passively ride, while a man, striding actively forward, does the work required to power the machinery.-- pocmloc, Jul 28 2011 On the strenuosity, it depends on the system frictions and the balancing mechanism. If the travelling compartment is perfectly balanced, then you need to do the same amount of work to raise yourself as if you walked - plus friction, but more efficiently (pedalling). On the other hand the counterweight could be heavier, so that you have to work to descend, which makes your effort to ascend considerably less.-- pocmloc, Jul 28 2011 random, halfbakery