I tell people it's very similar to Tai Chi, except that instead of a few dozen movements done one after the other, it is one movement repeated over and over for a period of time. Then I tell them that, like Tai Chi, it is a form of moving meditation that calms the mind and relaxes and re-energizes the body.
If they're still curious I show them one movement and invite them to try it with me. I have them notice how their internal dialogue slows down because they're concentrating so hard on coordinating the movements and timing them with their breathing that they don't have so much time to talk to themselves. The people I've spoken to have responded to that approach.
Going into details about chakras and chi is usually more detail than people want, and I've found it tends to put them off a little.
That's a good description and its pretty much how I see it too.
