Discipline is simple, yet powerful word. However, the meaning can vary from person to person (Remember that practice is always different from law :)). The same applies to programming.
When writing code we never exercise importance of meaningful and precise comments. I have seen many code snippets on Geeksforgeeks and other forums. Most of the code snippets posted by readers are missing comments. Readability, maintainability (simplicity), clarity and generality are key to write elegant code. Brevity also key principle of writing code.
Note that geting it right (or code is fine since it is working.... bla bla) are poor reasons to convince ourself. Accept comments if they are adding value.
About 2 years ago, I had written a program in Perl script to extract symbol table from binary executable. It was about 5000 lines. Yesterday I reviewed it again, based on a call from previous teammate. I am proud that the code is well commented in such a way any engineer in future can take it forward. I could able to recap all the data structures, algorithms easily from the comments.
I would recommend to read The Practice of Programming by Kernighan.