If you are a walker, but it is too cold, icey, pouring rain, or even too hot to walk outside,10-15 minutes walking up and down stairs is about equal to a 30 minute walk on level ground. Always walk down the stairs at a normal pace, one step at a time. (Most stair accidents happen on the way down.) But vary your up-the-stairs walk by taking one step or two at a time, walk up sideways, right side first, then left side, or even run up the stairs. But... (click title for more info)
even going up stairs can be dangerous, so hold onto the railings. If you have bad knees or stairs are too strenous for you, walk-in-place (without the stairs.) Vary your walk by raising knees high, kicking back your heels, stepping sideways, skipping, jogging, lunging, etc.