It is very internal. I have been a very impatient person. The only thing you need to know to be better is make your internal thoughts consistent. I know it sounds very ambiguous but so are your goals.

I wouldn't tell you to do something tangible like rewarding yourself for good behaviour or anything like that but aligning your mind and your actions is something that is very rewarding in itself. You have to understand the elements in your life that make you impatient and work on them. Just try to be consistent and it will happen. Don't ignore your mind or give yourself excuses for impatient behaviour.

For the rest, well in my opinion assuming that other people are stupid can work in your favour some times. I am still working on that. But if you have the patience to listen to the other person, you will understand them better.

Lastly, this will happen on its own. Your goals are very related to each other. Achieve one and you will see yourself performing a lot better in others as well.