Some days are a lot harder than others.
When I'm feeling particularly helpless, even the most simple tasks seem like mountains to overcome.
I have a problem with putting too much pressure on myself to achieve a set number of things in a day, and when these things go undone, I feel as though I've set myself up for failure.
That is why it's important to give yourself a push on those days that seem worthless, even if it is just brushing your teeth and washing your face.
I try and surround myself with things that I know boost my mood even if only a little, such as music, cooking or reading. Those little steps I have taken in the morning have provided me with the energy I need later in the day, whereas if I'd wallowed for hours and wasted the morning I would've undoubtedly felt worse.
So I suppose my advice is to not put unfair pressure on yourself, and to take those dark days one step at a time.