During acute depression, avoid trying to set your whole life in order all at once. If you take on assignments so heavy that you are sure to fail in them at the moment, then you are allowing yourself to be tricked by your unconscious. Thus you will continue to make sure of your failure, and when it comes you will have another alibi for still more retreat into depression.
In short, the ‘all or nothing’ attitude is a most destructive one. It is best to begin with whatever the irreducible minimums of activity are. Then work for an enlargement of these—day by day. Don’t be disconcerted by setbacks—just start over.”
LETTER, 1960