Inner doing is effort, which translates into mental and physical tension. It is an “idea” of doing, a mental state of worry and trying to make things happen. Real doing is physical activity, which can only occur in the present moment with our body, in coordination with the linear progression of time.
In each moment our body is engaged in some activity, continually transforming into the next and the next and the next, organically and fluidly. This is the only doing that can ever actually take place by a person, and it can only be executed by our body, which is truly the only form we come in.
Thinking is a type of physical activity but the sensation that the act of thinking creates (what I call inner doing) manifests as tension. Real doing is the activity we find ourself in in any given moment. It can be the only action for that moment because we each only have one body to act with.