It's not obvious? His grin hasn't quite faded yet, as he stands tossing the rock idly in one hand. Han takes a moment to scout out the landscape, finding the rest of their party and making a mental note of where they are, then nods his head in the other direction. It's a clear path for quite a few meters.

Just a father and son playing catch, right?

"Running start."

Moving target, moving shot. If he makes the shot and doesn't use the force it'll be blind luck. Still worth practicing.