It may seem a strange way to go, but I'd start with meditation. The more "present" you are, and the less your caught up thinking about past and future, the more

It may seem a strange way to go, but I'd start with meditation. The more "present" you are, and the less your caught up thinking about past and future, the more opportunity to be responsive and playful. I'd say there is an arc to this process (though I'm not an expert, so you'll have to do your research). I think it starts with just noticing calm, then bring in gratitude. The more you appreciate things, the more you'll recognize things to appreciate, and when you find anger or try to understand deeply why you have anger (or other emotion you don't want), and then figure out how you can replace it with a feeling you do want. Also, when meditating, I'll also sometimes meditate on a feeling like playfulness or joy, and just "feel" what that is like. Not thinking about what brings the feeling, just really trying to remember what the feeling was like and get my body to feel that way physically, not mentally. I think it's great that you've recognized this in your child, and that you are conscious enough to appreciate it. It could be an interesting teacher -> student cycle where you're learning to be playful from him, and at the same time, you're likely to tech him to continue to be playful.