As a founder, how do you overcome moments of self-doubt ?

You wait. And then, if you truly believe in yourself, motivation will come back the next day

I usually do very simple tasks that do not require any strategy I can doubt of. I write articles most of the time. Also I like the idea of the rule of 100 days. You do the work for 100 days without even looking at the results, just do the things blindly. This way you avoid the doubt due to the lack of results ( at least during those 100 days )

Self-doubt is common in founders, but it's a sign to iterate, not resign from your vision. Seek out mentors and advisors and run your ideas past them. You need to remind yourself that building a startup is a marathon, not a sprint. Keep a log of achievements handy to revisit during doubt spirals.

Well self doubt is a part if every entrepreneurs journey. Always stay focused. talk to friends or community members. most of all believe in yourself and keep affirming that you are going going to make it. Good luck 👍

I remind myself that this is normal. Sometimes, it doesn't help, so I go running. This doesn't always work, either. If so, I take 1-2 days off.

Reminding myself why did I start with the project in the first place. And then as @samuel_rondot already said, finding simple tasks that are enjoyable regardless of the outcome - to boost these dopamine levels :D

Honestly, I've found myself giving up a couple of times.

I think you have to be super resilient as a founder to be successful. Gotta love your product and be extremeley driven

Being present. Letting the past be in the past.