Though we've discovered that "Zen room" amenities in high-end NYC buildings rarely get used, we'd bet that most New Yorkers could benefit from bringing a little bit more calm into their apartments.
To give your place more of a Zen feel, Apartment Therapy suggests taking cues from your favorite yoga studio. Ask guests (and anyone who lives with you) to take off their shoes before entering. It makes for a more homey feeling and cuts back on noise. Hide technology as much as you can when you're not using it (and make sure cords are tucked away at all times).
And in a place like NYC where you're unlikely to have a view of nature from your window, adding a green plant or two can do wonders (and employ these tricks to make sure you don't kill them).