To enjoy the activity, it should provide a clear goal and a fast feedback. However, for many Flow-inducing jobs there is no immediate external feedback.
In such a case, it is important for a person to have internal feedback loop. This is the feeling “Am I doing good/bad?”
This requires the person to be able to recognize feedback and see the goal. Which is something that can only be achieved at Proficiency stage of × Dreyfus model (1980).