The intention of the sort of general, vague, "positive" advice, that people who aren't suffering from depression syptoms offer is to be supportive--but it often has the opposite effect, simply because the inability to follow the advice feeds into the profound feelings of hopelessness and powerlessness that define depression.

Even mild suggestions like "get out and about" can be threatening, since, when in depressive states, many people suffer panic, dread, and extreme and situationally inappropriate fear when they go out.