Use the stairs instead of the elevator whenever you can. Elevators are one hell of a convenience particularly if you have to go up or down some twenty floors. But elevators also make us very lazy.
There may be no sense in trudging up some twenty flights of stairs because by the time you get there you will be totally pooped. But while coming down, if you have the time, you can easily come down the stairs instead of using the elevator. Coming down is not at all exhausting.
And talking about the time factor, I don’t think that there is much of a difference. Sometimes waiting for an elevator door to open at your floor after you hit the button can take up all of eternity.