There's no point in focusing on the money/wealth that I didn't earn over the years because I took this path and I made a choice to. What matters is the here and now. That's not to say I don't plan for the future but I boiled it down to a simple trick to keep me going - is there progress? Is your trajectory up or down? If up, no matter how small or slow the progress is, keep grinding away another day/week/month. We're slowly adding customers, slowly improving our product to be indispensible to our current customers and getting paid on a monthly basis for it so there's a pin-hole of light at the end of the tunnel. I've already paddled half way across the ocean, I just have to keep going on.
I've found this to be the most dangerous type of thinking. It's always going to take longer, go worse and be harder than any of your best estimates. When you don't meet your dates or metrics, that's when you'll lose your motivation.
The key to keep grinding away relentlessly on a project is to improve habits and systems for making progress. The creator of Dilbert wrote a great book about it:
https://www.wsj.com/articles/scott-adams8217-secret-of-succe...
Personally I don't consider myself successful, but because of the advice to stop making goals I'm failing faster, staying motivated and getting stuff done. So hopefully eventually it will pay off.