(Insert difficult but attainable goal) will make me happy I'm not sure if this is common with dysthymia, but I'm just reflecting on how this was probably the "functioning" part of my dysthymia. 
Goal setting has always been stressed, whether by school growing up, or mental health professionals. Over the years I have had a vicious cycle of: setting a goal, planning it detail by detail, succeeding in goal, being hit harder when I'm still depressed after.
I remember quite a few years ago (I was diagnosed with MDD not dysthymia yet)  describing This to my therapist and asking when it would stop. She said I would most likely struggle with it my whole life, this was kind of the last straw before I began planning my suicide. 

I'm not really sure if I'm asking anything at all.