I just resigned from an early stage startup where I was the CTO. I burned out. Last summer I started asking our CEO if we should raise money to help us (basically me) deliver but he said it's too early as we didn't have many paying customers back then and the valuation and terms wouldn't be optimal. I hanged there 6 more months but in the end was so exhausted I took one month of sick leave and during that I decided it's not worth it to keep on fighting. Now he's raising money with a new CTO-candidate. Lean is good but I wish it wasn't my mental health we paid the leanness.