I try to stay as positive as I can day to day but there are times I just cannot shake a mood! On these days even doing things I love like seeing friends, lunching and dancing do not help so sometimes it is better to admit defeat and give up. If I'm working or at college I will finish my shift, cancel my plans and go straight home for bed and a cup of tea (maybe stopping for a bar of chocolate).
This downtime is so important because if we trudge on without allowing the odd lazy day/evening then the deflated, tired mood can fester and be harder to lose. Being completely unproductive can actually be the best thing to do! Allow it to happen without beating yourself up and try to start tomorrow refreshed :)
Happy sleeping!