your problem is not focus or willingness, it's being motivated by excitement rather than perfection. it's about the object, take yourself and how you feel out of the equation.
This is also a personality trait. Where ADHD has this in the extreme.
I, having ADHD, cannot do any task if it's not motivated by excitement and newness (or forced by raw discipline, which is extremely energy consuming).
Your comment sounds like "it's just a matter of changing your mindset". Maybe I read that wrong. But I know it's not just mindset changing. It's, e.g. with ADHD fundamentally wired into a brain.
your problem is not focus or willingness, it's being motivated by excitement rather than perfection. it's about the object, take yourself and how you feel out of the equation.