As the closest friend of someone depressed, I have to say such illness isn't the same as physical illness. Sure all those advices won't change anything, but that's just because the person doesn't have the will to make them happen. People around the depressed person can definitely help, just by spending time with the person, and encouraging the person to accompany them to activities. Biggest danger is insisting too much as you might turn into a burden. Sometimes I think it's just better not to talk