Took the decision to start from a blank canvas around last September, and up until February I only recall having several days off (Christmas, NYE etc). Worked in the day, the evenings and weekends. Impending sense of doom only seemed to subside when I made progress - this feedback loop kept me hooked and driving forwards.
Launched the site (https://www.construct.net) a couple of months later, but it burnt me out. Had to take a fairly significant amount of time off to switch off. I was waking up in the night with a horrible twisting in my chest and random bursts of adrenaline. Not healthy!
The site has been up and running and selling now for months really well, so I am proud and relieved.
Benefits:
* Learnt how to make a scalable site
* Re-writes are always significantly better written
* Learnt a LOT
Downsides:
* My health!
Also, you can't retrofit scalability which is a lesson I learnt the hard way. Seems obvious but I had a years work at stake so had to give it a try and having the guts to scrap everything and start again was incredibly painful but has worked out well long term. Feels very comparable to learning to backup.
When I look back at those several months - I honestly remember very little of it. As our startup has grown we've also learnt than I'm now becoming a significant bottleneck as my bandwidth isn't unlimited and it's a huge relief that we're now taking steps to address this.
I'm also not someone who can easily ask for help and leave it until it's too much to handle. This was a big contributing factor.
Not a "spectacular" burn out story but I teetered very close on the edge of something quite negative - I'm not exactly sure what but I'm glad I avoided it.