Poker psychology (especially in live games) is actually a strength of mine and I have confidence that when I make a big laydown, it is correct (many times my opponents will show me I was right by folding face-up) yet counter-intuitively, I am also humble enough to realize I am not right every time. I think this is something you see good players do: easily admit "hey, I might be completely wrong" about this read, play, situation etc. I believe that when you play without the fear of being wrong (or ego getting to yourself) and just play your best: you play better; at least I've noticed this works for me.
As far as
knowing (with really good certainty) that you are beat, but can't fold the cards (committed to the hole cards or whatever) then I recommend a training drill I've done a few times before and I think it helps. When at home, or have some down time, grab a standard deck of cards: shuffle the deck and then deal yourself 2 cards face-down. Then look at your cards like you were actually in a
poker game. Do you have pocket Aces? No? Then fold. Keep repeating. Over and over...and over again. Finally get pocket Aces (even if it took an hour)? Great. Now fold the pocket Aces too.
The game is "over" when you fold Aces. Why do this? Obviously it tests your patience, but the goal is not to turn you into a super nitty player: the goal is to really "feel" the feeling of letting the best
hands go and it being okay. Before you pick up pocket rockets, you will probably get other really strong starting hands that you probably wouldn't fold in a game. Pocket Kings? Fold. Ace, King suited? Fold. Jack, Ten suited? Fold. You get the idea. This drill sounds time consuming (and it usually is), but it really can help you "learn to fold" the best hands. This is especially helpful if you really put yourself in a poker game mentality and imagine playing a real game during this drill: we are simulating a real game environment.
After trying out this drill: put this skill to use in a real game. Real game hand number one: you look down at pocket Aces on the button. What do you do? Fo...No! Probably not; play it with common sense. What will happen after trying this drill though is that you may find yourself in a marginal spot (or a situation where you should be playing tighter poker) and you will find folding hands easier - especially if they are on the fringe of playable or not.
This drill will have you fold many premium hands; play those most of the time in a real game, but it will teach you discipline to fold if you have a great hand yet strongly believe you are beat.