You have always endured the pain. It is a constant capacity, not a one-off discard. So you have what it takes to make it, at most you die trying your best.
You have an annoying lifetime habit of intellectualising chronic visceral discomforts, but in narrow-minded vicious loops, like a roof cave-in unto yourself. Be true, flow naturally, not try too hard to prove thyself, then do too much, burn out, and doom yourself drowned in too much dread, for too long.
And you take for granted your second winds, when you should be grateful you're alive another day to strive again. Rest and recover, then resume, tiger 🐅 . Most don't bother to keep trying so hard, just to get so many basics done, and then take for granted the efforts of others, and their own entitlements .