I've used this quote before, as I come back to it repeatedly. I think there are a few ways to create those gaps -- like hiking (or just being in nature and letting it soak in) or exercising (and yoga). DH definitely finds his in mountain biking, where he's so focused on the task at hand that there's no room for anything else -- leaving huge portions of his mind free to wander and experience.
I also can find it during a shower or cleaning house -- something repetitive which takes no real effort or deep thought...and today, I have a very full morning ahead of me, but I'm starting it out with the gym. I'll definitely look for some gaps!
How do you find inner space?