I've lost huge groups in the fuseki but kept playing and came back and won. That is way too early to resign.

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We don't know who we are; we don't know where we are.
Each of us woke up one moment and here we were in the darkness.
We're nameless things with no memory; no knowledge of what went before,
No understanding of what is now, no knowledge of what will be.

Did you see Hikaru No Go episode 64 "Keicho Flower Bowls" ?
It's one of my favorite... of course that's fiction but I liked that the opponenent resigned
and then they exchange side and Saï can still won the resigned game.

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Converting the book Shape UP! by Charles Matthews/Seong-June Kim
to the gobook format. last updated april 2015 - Index of shapes, p.211 / 216

I'll have to check that out, but that's one idea to use if you are the type to resign too early. Imagine the won games you have lost and the kinds of mistakes that can happen to you. If you are ready to resign, it also means you can confident of winning against any of your normal opponents if the tables are turned. Maybe you don't have to take it to the extreme and say "okay, I'd even beat Cho Chikun if we switched sides" because then maybe you'd never resign.

You can always ask a teacher later if you keep the game records. I remember many games I gave to my teacher and as we went through them I said, "and it looks terrible, so I just resigned here." Usually he would say, "yeah, that's the best thing" or "about time!" But once in a while he would say: "Hmm. Let's see how far you are behind..." He would then play out the endgame quickly and count. I would still be ahead. Now he was playing both sides by himself very, very fast and I wasn't strong enough to see whether he was messing with my head and favoring one side, but he definitely made his point, which is that if I felt bad, I should take a breath and count the score dispassionately before doing anything rash. It's all okay. I learned go from the games I resigned correctly. I learned about myself from the games I resigned too soon.