Being uncomfortable leads to guilt and a sense of failure for good reason: You DID fail. Be honest.
How you handle failure tells a LOT about your character. Either you're a pussy who sits in a corner feeling sorry for yourself, or you take your lumps, then get up and go again.
Feeling warm and fuzzy all the time doesn't give you grit.
This formulation of grit is overrated / should be considered harmful. Your macho attitude and glorifying of "toughness" is a very stereotypical[ly western male] characterization of strength. You mention being willing to take your enemies down with you, fighting with a broken rib, and call not accepting feelings of guilt / failure being a "pussy" (which btw is also demeaning to women).
Yeah, starting companies and going into debt incurs stress. Having social conflict incurs stress. But dealing with that stress does not ever have to entail blaming yourself or white knuckling to get out of it. Telling an alcoholic (chemical addiction) to just "STOP DRINKING" doesn't work because people just don't work that way -- similarly, stress is chemicals in your body and there are procedures known to reduce it, and healthy thought patterns to move systematically toward a better situation rather than unhealthy "STOP SUCKING" / "WORK HARDER" signals. Those are not actionable.
This post is not actionable. Cool humblebrag, but it elicits no respect from me -- real grit is having the patience and perseverance to discover functional processes to better your standing. It requires no anger, killing of enemies, or broken ribs.
TL;DR Learn to problem solve better and maybe without calling people pussies. Maybe you'll be happier for it and live more empathetically toward others.