I have found at times it helps to just accept sadness as your focus for one whole day.
No happy slogans, no motivational reading, no self talk about look on the bright side, no practice of gratitude. Just sink into sad. Accept it, embrace it and allow yourself to feel all of the aspects of sad without judgement.
A funny thing happened when I gave myself a sad day. I felt free of responsibility. I felt content to achieve nothing. I felt relieved at having nothing on my to do list. I did not worry about how Lee felt. I did not consider who needed anything from me. It was almost like a release from all the other days when I pretend everything is great, fine and I have no worries.
I think it would be a better balance to acknowledge sad feelings as they appear on a regular basis. If I were better at allowing feelings to surface and pass along, I might not need a whole day to be just sad. Until I am able to do that one sad day when ever I feel the need to just be sad seems a reasonable compromise.