There aren't any nearby leaves, and Xel lets him down with a noncommittal "Is that so?" as he turns away slightly to touch his forehead, heart, and lips (which are tugging a bit upwards at the susurrus) before sending the kiss skywards in a moment of informal prayer--although in situations like this, perhaps communion would be a better word.
"Not too bad," Xel says brightly just behind his ear, keeping pace without the slightest hint of labored breathing or even an audible footfall. "But try keeping your arms streaming behind your back instead of pumping them like that. You'll waste less energy and be more streamlined."