If you are in a similar boat, it's likely that when you consider an upcoming dreaded task, there is at least a small part of you that admits the possibility that you will not do the task . And because there is, and because your brain realizes it, it expends mental energy trying to convince you not to do it. Once you are actually doing the task, or it's done, or you realize that you must start doing it immediately, yo…
I don't agree with a lot of Alcoholics Anonymous' philosophy, but the concept of 'white-knuckling' is quite a powerful metaphor for the trap we get into of trying to force ourselves through a difficult activity, and it speaks to a somewhat tortured value judgement around the relative value of doing a task at all versus doing it yourself. Like you'd rather have mold in your house than pay some guy to fix the shingles on your roof.
I've consumed as much if not more of my favorite ice cream in the last year, but it tends to be reserved for conscious choices: I'm going to make a difficult phone call or work on my billing, then go for ice cream, rather than whenever I just feel stressed. It is certainly not the only tool I have added to the toolbox, but it complements others and the end results have improved my outlook. And since motivation and mood are spirals (which I think you were trying to say?), that's a big deal.