Not OP, but you have to keep in mind that your body is always trying to repair any damages that happen. Be it through actual accidents or molecular mishaps. Stress and other factors can cause the body to go into survival mode, where all resources are allocated to solving only the challenge directly ahead at the expense of repairs. And your body always needs repairs, because there is so much stuff going on at the molecular level that wears down the cells. Our bodies are pretty good at repairs but not perfect.

I worked myself into the dirt for 2 years for a start-up that ended up failing. It felt like I aged 10 years. My hairline receded an inch - my hair started going grey - and I gained 15kg.

I'm undoing the damage now - but I can tell I've been physically aged by the process.

Our physiology is not built to work under sustained high stress and a constrained environment like fast moving startups can have long term health effects.

1: https://www.goodreads.com/book/show/18693771-the-body-keeps-...

Stress + neglected diet and exercise definitely puts a strain on your body.

if you doubt that, I recommend living under high stress conditions for a couple years and see for yourself

It definitely does, but even a decade of high stress vs not having to worry about money for the rest of your life could be a very fair stress trade.