Between activities, the body strives to conserve energy by using itself as a brace, a platform, a pedestal. A hand cradles the head so the neck can rest. An arm settles at the side rather than being permanently suspended. Alleviate puppet-like stiffness from your poses by letting go of (or at least loosening) some of the "strings."
Drawing notes : Drawing contact is a challenge, but don't be afraid to obscure/overlap large parts of the body to achieve a look of relaxation. Accept that you can't show everything; in fact, it's best that you don't.