Adults often call play childish after forgetting children are excellent at being alive.

Children are not bad at life, they are unusually good at parts of it: absorbed attention, immediate delight, willingness to look foolish, complete presence in what they are doing. Calling that childish is a way of avoiding it rather than a judgment on its value.

Watch a child do something and notice what they have that you have lost. Usually it is the absence of self-consciousness. You are not going to fully recover it and you can recover more of it than you currently have.