I think of them like visiting, and not being "mine". Also, I try to view them as full individuals that are already grown up, and in some ways have surpassed me in ability and wisdom.
It helps me keep on track in how I talk to them and how I behave. And not least, how I think about them and our time together. It makes me more of an ally and guide than a top-down dictatorial parent. I hope. I think.