What techniques do you use to prioritize the features of the MVP?

I ask myself what is the single most important problem I am trying to solve with the MVP. Once I isolate that I brainstorm all the sub-features I need to solve this problem. Once I have these sub-features I organize them so that I can focus on the features that will get me to the solution quickest. Anything after that is a nice to have and I don't focus on them unless the MVP is literally broken without them. This allows me to focus on the primary feature to solve the primary problem my MVP is being built for.

Well this is how i always ENVISION my MVPs going. Then I start building and get feature ADHD and build much longer than I should for an MVP. The method is sound, but my execution is faulty.