A lot of discipline is patience and getting accustomed to how often premium
hands actually show up (pretty rare). I don't do it so much now, but when I started out, there was this poker 'drill' I would practice by myself...
Take any 52 standard deck of cards and shuffle them. Then deal yourself two cards. The key with this drill is to treat them like you would cards just dealt to you in a real game. You can even imagine a real game going on and the dealer just dealt you those cards. See your hole cards? Is it pocket Aces? No? Fold it. It could be 72o, or it could be QQ, but you fold EVERY hand until you pick up Aces.
After you fold, shuffle the deck and deal yourself another two cards while repeating this process of visualizing yourself in an actual game.
Finally, you pick up AA. Might be just a few hands if you are lucky, or it might be half an hour later. Now that you have the coveted AA...fold that hand too! The drill is complete when you fold AA.
Yeah this sounds time consuming and silly, but you'll be surprised at your patience and discipline after doing this drill every now and then and especially so if you really visualize the game and treat it like you were just dealt those cards. I'm not trying to turn you into a NIT, but you'll "feel" a strange feeling folding hands like AKs or QQ. At first you might feel like, "nooo..." as you let them go, but eventually you'll be able to fold them without any hesitation.
In a real game, of course you'd likely play these premium hands (they don't come around that often, so we must make use of them), but this drill will teach a lot of preflop discipline and make you more open to folding in real game spots you should be tightening up. Perhaps on the money bubble with a small stack, or maybe a mountain of chips to your immediate left.
Don't be too critical of this drill until you try it out a few times; it really can help build some folding discipline and similarly discipline with choosing what cards to play and when.
