I wouldn't call myself a ruthless executor, but I do tend to ship more projects than not. The last startup I co-founded was acquired about 5 years ago, and my current startup is doing well so far. This is a long post, but it hopefully ties together by the end.

One thing I've noticed though is that it's hard to actually categorize people as ruthless executors and as being completely self-motivated without knowing the actual details of their situation. While it's true that some are better at it than others in relative sense, I also think it's true that a significant amount is affected by situation and occurrence.

What I mean is that, it's often easier to maintain motivation when people are using a product, giving it praise, when it's growing and/or making money, and a host of other things. You may see someone you think intrinsically has a lot of self-motivation, but maybe they're just better at recognizing and fueling themselves from small victories, and they know how to get those victories, small or large. This can work the other way too though, as sometimes these victories are complete luck and happen as unintended consequences from the things you do or people you know.

It's easy to look at two people who started two different projects two years ago; one has grown their team to 10 people and making a lot of waves, the other gave up on the project 6 months ago; and think the former is a ruthless executor and the latter is not. But maybe the former person had no more traction than the latter 6 months in, but they met someone at an event who connected them with their first paying-customer-to-be, then they met with them and got a lot of valuable feedback which motivated them to release an MVP especially for that customer, which then garnered two more customers, which motivated them to spend some time marketing, which led to more customers and so on. Maybe the former person would have given up after 8 months if none of this had happened. And yet the latter person didn't get any of this and yet still persevered and remained motivated for 18 months absent these external motivators. You could argue the latter person is more self-motivated than the former.

I guess the thing I'm getting at here is, there's a difference between being motivated and being self-motivated. Self-motivation is necessary to persevere through the times with not external motivators. But in the long-run, which is what you're asking about, it's not enough. You need external motivators, too. This is where co-founders can help. This is also where customers can help. Both of those are difficult to come by, and require knowing and meeting people, not just building things.

That said, there are a few things I've noticed that really help with self-motivation in the time that you need motivation, and here is a list that may be particularly appropriate at the "25-50% of the journey" mark. Again, these won't get you all the way there, but they may get you far enough to the next external motivation milestone to make a difference:

1. Get a graphic designer to create an actual, polished design for your interfaces and/or landing page. It's amazing to me, how much I and my team, as engineers, are motivated by how polished and "official" something looks. It can be a renewed wind in the sails.

2. Create documentation for it. This can be as simple as a README or as involved as a launch-ready landing page. Even just opening a new Google Doc to start writing is a big step forward, and you'll need it eventually anyway.

3. Once you've got some screenshots or the semblance of a README, post it on a local startup channel or message board. It might not yet be ready for prime time launch of Product Hunt or Hacker News, but I find local communities to be much more supportive of works in progress, and valuable sources of feedback early on.

4. Take a scheduled break from it. Having a separate hobby that has nothing to do with software can be helpful, whether it's sports, crafts, music, or whatever.

There are probably others, but this might be enough to get started. That's actually a great segue into another technique that helps me. Often times when I'm lacking in motivation to get something done, I find myself thinking of how far I am from the goalpost, and since I don't have a clear vision of how to get there, I stop working on it until the vision comes to me. This makes it hard to get back to it though, as the complete vision may never come until I make more progress... sometimes the vision doesn't come until I'm already there, at which point the vision is only clear in hindsight.

To counter this, I've started distinguishing between things that are only valuable when complete versus things that are valuable even when only partially completed. If part of it is useful, then go ahead and do that part.

The above list, for example, may be useful even though I only listed the first four things I could think of. I almost didn't write this post, because I don't have time to refine my thoughts or complete the list. But it's just a post on a forum, so anyone is free to read my long, unrefined post with an incomplete list, or skip it. So, I might as well post it in case it helps anyone. If enough people find it helpful, maybe I'll come back some day and use this as an initial outline to create a more complete list with a more refined message.

Anyway, I hope this helps. I'm not sure if it answers your question exactly, but these are some of the things I think about when considering my own ebb and flow with motivation.