Hmm. You can get learn about how to apply dicipline from books but motivation is a different story.
Motivation is the will's little sister. If there's will, there'll be motivation, if there's no will, there'll be no motivation.
When there's motivation you can apply dicipline, but when there's no motivation, you can learn in theory all about dicipline but you can't apply it long enough.
It's like a cycle, one thing leading to another, depending on another, and so it goes.
Perhaps you might want to check if there's any of the main ingredient required to cut the mustard... the will to cut the mustard.
Perhaps what you have in stock is the will to cut the catchup instead, or the mayo, or the barbecue sauce... Always best to double check before going and start chopping things in the kitchen. ;-)
"Wer Nichts Wagt, Kann Nichts Verlieren"