There is a thing that J K rowling has introduced in Herru potter and the prisoner of azkhaban called as dementors
dementors r the creatures who guard the wizard prison in azhkhaban.Whenever they r around they remove happiness from u.they leave behind only bad memories.
does'nt this thing sound similar to depression.
Harry saves himself from the dementors by using imperious patronous.For this patronous it is important for harry to think abt a happy memory.the more happier the memory the more strong is the patronous.
So this is the way we too deal with our depression
They only way to be happy in our life is to always save our happy memories.
During the feast dumbeldore says happiness can be found in darkest times if keep the light on.and this light is the hope.