Depression very commonly accompanies just about any kind of chronic ailment, because it is hard not to be able to do things, whether they need to be done, or are wants rather than needs. It is also depressing to be in pain all the time. Depression can cause other problems such as lethargy and apathy. One of the best remedies for depression is getting outdoors and being active, so I think it is essential to plan and organize a property to make getting outdoors and doing things not only easy, but difficult to avoid. At the same time, you can’t make the work be too much for a person with health problems and physical challenges.
Possible solutions might include: moving to a climate conducive to being outdoors as much as possible (will vary depending on what kind of climate each individual prefers).
Designing living quarters that both include the outdoors, and encourage being outdoors (an
outhouse, multiple buildings, courtyards, covered decks and patios, outdoor summer kitchens, gazebos, wrap-around porches, and so on).
Make it easy to work outdoors, with level paths, good spacing for passage between beds and plants,
water and power where needed, low-maintenance everything, good views and things to attract the eye, the nose, a touch (you can make good views even on a
city lot by the way you arrange walkways and plantings).
Personally, if I am going to be outdoors, I want privacy - I don’t like to have strangers looking at me. So if I lived where there was a lot of traffic past my place, foot or car, I would want some kind of hedge or
fence - or a ‘fedge’ - before I would feel comfortable in my own
yard.
There are undoubtedly other considerations that didn’t come to mind, but this would be a start.