It's all good, and I'm genuinely enjoying these interactions here on HN. Literally nothing to lose and everything to gain from the dialogue, and I do help it's of some benefit to others :)

Part of how I have rationalized my journey so far is that I have been building an app that I myself use almost every day, I genuinely enjoy the building products and working with my team, progress has been steady along the way, and I have unwittingly over-indexed on my own judgments as an "efficient proxy to the market".

I know that might sound crazy, but it's a bit like, "We're making progress, but it's not quite ready, so let's just keep building. I know this is good! We got this!"

In terms of more specific reflections and lessons learned so far, here are a few initial thoughts if I could start over again, knowing what I know now:

- Co-Founder: I would not do this over again without a co-founder with passion and expertise in for B2C product marketing. (Even to this day, I've never really had good access to someone who has successfully bootstrapped and monetized a non-trivial digital product app from scratch.) In addition to the moral support and general collaboration, this skill set would be complementary to my own. It would had the potential to be a great counterbalance in the overall approach to GTM and product strategy.

- Financial Accountability: I'd create some semi-formal accountability structures with "gating functions" for how/when funds could be spent on the product along the way. Conceptually, before taking on another 3-6 months of committed product work, make more aggressive contact with reality through user interviews. Much of the product evolution has been pretty fluid, organic, and linear based on small inputs along the way.

- Proxy Users: I'd recruit a small group of users (compensating them a small stipend if needed) just to stay active on the app (e.g. you're going to be working out anyway, so do it with the app a couple of times a week) and provide regular feedback about what they see that they like and don't like, what's confusing, frustrating, etc. Probably too much of the UI/UX has been dialed in from my own experiences, and there are some interactions that can be reframed to be more obviously valuable based on the input of others

- Likelihood of Success: I'd question whether the scope/complexity of what I set out to do as a solo founder with limited funds can really be achieved. For example, how likely is it that I as a solo founder can bootstrap a B2C consumer-grade iPhone + Apple Watch to profitability? And in what is considered by many a "crowded space". (It wouldn't be wrong IMHO to characterize a certain district of the app store as a 'wasteland of fitness apps'.) Should I be trying to bootstrap something this complex in this space at all? Or decrease the scope? Or consider a different financing approach?

- Resist Perfectionism: It might not be obvious, but keep in mind that I've been thinking about GTM a LOT. I just haven't been doing GTM to the extent that it now seems obvious I should have been. I have somehow been rationalizing that I just need to "build more" to get the product "more ready" before I start leaning into a space and set of activities I don't particularly enjoy and am somewhat uncomfortable with. (And instead, I've been continuing to do the things I am good at and comfortable with.)

- Less Isolation: And even as I itemize all of these things, I can't look back and think of any specific moments were I ever thought I was making an egregious mistake on any given day. Every day, I made what seemed like reasonable/good decisions with the best information I had at the time. Being less isolated and more integrated into a community of practice to share progress might have made a difference

Probably lots of other things I could say (and let's not forget there are lots of other draws on my time in life with family, etc.), but those are some initial thoughts that I can share.

If anyone bothered to read all of this, I hope it's of some help!