Digimon World

Not really, Discipline takes time to raise, the fastest way I have raised it was by scolding it when it refused to eat a stat raising chip, autopilot or portacrapper, scolding in general raises discipline but lowers happiness if it isn't warranted, and after a certain point your digimon will not refuse items no matter what they are.

There are also probably some dishes that raise discipline as well, or you can use those stat dishes to counter scolding happiness loss quickly if you can't find any blue mushrooms.

Try always using porty pottys. If they refuse scold them. then walk a bit and try again. sometimes they will refuse again and you can scold again. This can rapidily increase disclipline into the yellow face at least

Use blue apples and happymushrooms. Then once his happiness is up really high, you can scold him all you want and he won't get sad.

This usually works best for me, at least.

Well, whenever my digimon refused an item (autopilot, stat chip, porta potty), I would scold him and it would lower its head instead of yelling back and it would raise discipline and happiness to a great amount. This worked a lot in the beginning and by the time you have champion/ultimate digimon, their discipline will be maxed.

Here is a better way: FIGHT!
Also, make sure you make no care mistakes.

Only scold your Digimon when it won't take something important. Such as a Portable Potty or a Medicine. Otherwise, it will lower its happiness and it wont even learn from it. Its not a real pet! Lol.

So yea, these two methods are your basic techniques.

Buy Lots of Small Recoverys and when ever your Digimon refuses scold him. Small Recoverys are cheap so you can keep on using them. Also feeding your Digimon Blue Apples work. And try to get as least CMs as possible

Given those you mentioned, I guess scolding is the only answer. If'your digimon refuses, to take up somthing or refuses to sleep, etc...the good old scolding will do the job. Aside from that, just leave it as it is without compromising it as well, it'll do so increase in due time. You'll see...

Hey, the best way to raise your digimons discipline really fast is by feeding it with ice mushroom. It is found in freezing land. You just have to be patient in finding that mushroom thought.. ^_^