Fuzzy is normal.
What is good for one person can be profoundly bad for another, even if their goal is roughly the same. We each live within a unique set of contradictions and experiences that shape how we see the world.
Remember that there's no right or wrong way to do something. Words like right and wrong are subjective.
The important part is being honest about what you intend to accomplish within the complicated reality of your life. Your intent may differ from other people; you may perceive things differently.
You may be dealing with an indicator that's surprisingly difficult to measure, a data source that's grossly unreliable, or a perceptual baseline that's impossible to back up with data.
But as fuzzy as your lens can seem, setting goals with incomplete data is still a good way to determine if you're moving in the right direction.
Uncertainty comes up in almost every project. But you can only learn from those moments if you don't give up. Stick with the tasks that help you clarify and measure the distance ahead.