Sometimes you can just define what will be the perfect outcome for you and start working! However, often it's not necessary to aim for the perfect state. For example, if you are learning English, you don't need to reach upper-intermediate level in order to talk to others, even if that's something you desire to achieve. The beginner level will be enough for basic communication, and then if you want you can go further and advance your English. In this case, upper-intermediate is a “perfect” outcome, whereas beginner level is a minimum outcome. There is a term for that in product design — MVP, or Minimum Viable Product.
Define your minimum.
Just kill that perfectionism and aim for the minimum state you defined. No, you aren't aiming low in this case, because you still keep the perfect state in mind for the future. Instead, you are defining the first step that will allow you to start moving towards the ideal outcome. It's much easier to make small achievements, and to walk in small steps towards your goal instead of making a giant leap straight to the perfect state. It even will likely increase the speed. Let's return to the English learning example. If you were to start talking to people on the beginner level of English, wouldn't it then be much easier to reach your perfect state of upper-intermediate than doing it in isolation?
We all had to learn to crawl before we could walk.