"EFT" , Gary Craig's Emotional Freedom Technique, and "Faster EFT", Robert Smith's Emotionally-Focussed Transformation
are both really good to use while water fasting.
I too, OliveOil, experienced more happiness after fasting, and even during it. And crying too, which can be a great release, and doesn't even have to be about anything "negative". There are a zillion or so substances, hormones, chemicals, etc. in tears, and their release can be like the the symptom of the END of layers of emotional detox.
It makes sense that as the body autolyzes a lot of the old crud that has been stored away, a lot of it that is emotional waste, would also find a release.