Impairments in executive function are associated with autism, as well as ADHD, Tourette's, OCD, depression, and other psychiatric or developmental disorders. Motivation falls into that, so it just comes with the bag of tricks. The obsession is the flip side of the same dysfunction. [note: I'm using the terms from the literature, please don't read too much into the terms]
As far as coping strategies to do things that you are completely unmotivated to do? Personally, I try to focus on the reason that I need to do it. Is it required for school? Work? Exercising for a sports team? Staying focused on the goals can help make things seem more important in the moment. I also find that breaking things down into small chunks helps. You can pretty much do anything for 5 minutes. So, promise yourself you will start with a 5 minute chunk. Maybe if you get into a groove, you'll keep going. If not, you've at least done something.
Of course, I say this like I've mastered it. Looking back on what I accomplished at work today, I could do with a dose of my own medicine. Good luck!
--Odd_Duck
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"There is nothing--absolutely nothing--half so much worth doing as simply messing about in boats." - (Kenneth Grahame)
"It is not enough to have a good mind; the main thing is to use it well." - (Rene Descartes)