Physical symptoms of depression: The invisible ball and chain

Depression responds well to therapy, but can be much more difficult to treat if it's been going on for a number of years. For instance, a client may finally seek help at the urging of a friend, but has slowly fallen into bad habits that are really hard to change--a physical ball and chain.
No matter how much good therapy goes on in the office, if the client goes back home shackled to the same ball and chain, nothing will change. Wanting to change is not enough. The shackles must be broken.
What sort of bad habits make up the physical ball and chain? It is worth pointing out that half of the possible symptoms of persistent depression (PDD) in the DSM-V (diagnosis manual) are physical--sleep pattern, eating pattern, physical activity. A fourth symptom is primarily the result of these three: ability to focus. If a client is serious about treating depression, it is important to do a bit of "coaching" first, to address these issues.
Fundamentally, an old social work model is very applicable, as seen drawn in the picture above. One could describe the flow of "good vibes" as outward (positive engaging with the world) and inward (receiving the benefits of positive engagement). Any engagement is mental, physical, social, spiritual, or a combination of those.
The DSM-V and social work model are simply two ways of saying the same thing, only the latter is more specific about engagement with others, and defines "focus" as spiritual--engaging with the heart's desires.
Big note: there are healthy and unhealthy spiritualities, just like there are healthy and unhealthy physical activities! The model isn't meant to go that deep, but this reality is important to keep in mind.
So, to conclude, I work with depressed clients to ditch the physical ball and chain at the same time as discussing and disarming the more cognitive aspects of depression. It's the only way to get results. Insight cannot be applied when sleeping late or without appropriate food, not to mention that these bad habits are really part of the depression itself.