This is why I love marketing.
(ps. I got it from this great blog)
Notice, there's a decision being made here - the people creating these stairs have surrendered to a fundamental reality - you cannot (easily) change people.
You can almost only ever REARRANGE the world around them in order to produce your desired result. I can't decide what to think of this - whether to point out that this is a form of surrendering the real argument and resorting to manipulation to get your way, or to point out that you can only win the battle once you've accepted the things you cannot change.
Another thought occurs to me - there are two ways to illicit the action you seek, and they're based on the two types of people you face:
1. There are the people who at heart believe what you believe, but are so caught up in their own thoughts that they forget to translate that belief into action. For these people, a simple sign suggesting they take the stairs would make them aware of the choice they have in the matter, and they would take the stairs.
2. Then there are the people who don't CARE about exercise - these are the ones who you have to manipulate with those piano stairs.
And of course there are the people who have already bought in and are aware of it - they're the ones you love that take the stairs without any prompting at all.
If you find yourself in that first group (which I often do) - how can you raise your own level of awareness to live the way you want to without any prompting at all?