This sort of definition of "tough" seems a bit insulting to bouncers, cops and cage fighting champions. Like how the nerd definition of "risk" is an insult to soldiers, parachutists, and Evel Knievel.
I've seen many different people train over the years, and I think grit can be acquired. Hard training encourages it. But, on the other hand, I think some people start out grittier than others. I have some training partners who never really acquired much grit. Those without much grit in training tend not to have much grit off the matt.
This is a long way of saying that while those examples aren't particularly impressive, I still think grit matters in areas that don't require physical exertion.
Startups (and other intellectual and business ventures) are not sports though. This is a double-edged sword.
Sometimes "grit" means that you push through the tough parts. This is good, and absolutely necessary for success in anything. But sometimes it means that you fail repeatedly by making the same mistake repeatedly because you mistake self-reflection and course correction for weakness and refuse to learn anything.
I've seen plenty of people who are very tough on the axes you mention but were unable to deal with the stress of starting a startup.
When I wasn't outside working in the below-freezing weather, I fed a coal stove through this past winter because we didn't have a modern heater in our workplace. The ash turned my snot and phlegm consistently gray. Things are a little cozier now, but I still don't run the air to save on money - and Beijing is hot in the summer.
Adopted a dog?
I don't dispute that you did would take more grit than most people would be willing to put up with, but for heavens sake man a mask is what $0.5? If your phlegm changed color, what do you think happened to your lungs?
This talk about startup founders having to be "tough" just seems like an ego boost to make the whole startup experience feel heroic and epic, which I think is OK because a little self-aggrandizing is probably good for motivation.