It's true, I'm not a psychiatrist and don't know him. It's also obvious that achieving things helps us feel better. I'm trying to suggest that, instead of focusing on productivity as the final solution and trying to hack it into his life, perhaps look at the factors causing his difficulties. For example, the fact that he works alone, or does a sedentary job -- both of which are massive risk factors for depression.

We're stuck with his articulation, but I can see how that would seem to be the case. Personally, I see lack of productivity as a symptom of depression, but it's not for no reason that there's a saying, "the devil makes work for idle hands."

Point taken and agreed. Thanks for rephrasing.