Oversimplifying depression and the cure for it is not helpful to those who suffer from it. Depression isn’t simply a “negative attitude” that you can change with the turn of a phrase. The cure is not as simple as “go out in nature.” While they are not a cure, lending an ear or a shoulder, is more beneficial.
While it might be difficult for you to talk to or be near someone who is suffering from depression, I can guarantee, living with depression if more difficult. Ignoring the phone or avoiding themselves isn’t an option. Every day they have two choices: Fight the depression with all they have, (with medication, reading, writing, or therapy) or let it defeat them.