“Nature” means “that which happens by itself”.
It reasons to say that “behaving naturally” implies a behavior that is Not rigidly controlled by some outcome we may have.
It implies “flow”, “Play”, “letting go [of attachments]” and “Wu Wei – doing without doing”.
Obviously, we may have a Direction, an Intention (that is, Not an Expectation). However, when we “do the doing” – to the extent that we want to ‘be natural’ – we better “forget” about that Intention and our only “focus” should be Staying Present while taking action.