My typical cycle of execution is something like this
Find out something through HN/Reddit/Other medium --> Get motivated --> Get good knowledge about it through research --> See others succeed, get motivated a bit more --> Execute and get to, say, 25-50% of the journey --> Get bored --> Abandon --> be passive for couple of months --> repeat.
Be it creating new websites or new products (probably the reason I have not launched something as a personal project, despite having tried like 10-11 of them with varying degree of success), weight loss journey, running, meditation etc. I have tried breaking things into manageable chunks and then taking them one-by-one, or through methodologies like GTD, or by making others accountable (tough to find someone who takes personal interest in what I would do; also, I have strongly come to perceive myself as being driven by external accountabilities which makes me good at work at office but bad at executing personal projects).
I see folks who are disciplined, are ruthless executors, are self-motivated, and wonder, what could I improve or work towards to get things in a better shape. Any suggestions?
Some people are great at coming up with new ideas but quickly bore with the implementation. Some people can relentlessly improve on an existing thing but can't come up with the initial idea. Some people are great stewards of an established program but don't thrive in the chaos of rapid iteration.
I think instead of trying to mold yourself into something you're not naturally good at, you should try to figure out what you are naturally good at and build a team around it to support you.
I'm speaking in broad strokes of course, but reading your post, I think you are just not going to be a sole proprietor. You need a team member who can catch your early enthusiasm and then help see the project through to completion.
You need a finisher. Not every starter is a finisher, and not every finisher is a starter, and not every finisher is a good maintainer, either. They're different things.