[Marat]

As someone who has never had a habit of using swear-words, I think it had a lot to do with my upbringing. I would never dare to use those words in front of my parents. So perhaps you could benefit by spending more time with people in whose presence you would be embarrassed to use foul language (your mother, grandmother, other elders, teachers, etc.). You will also need to make an effort to be self-conscious about everything you say. Eventually, you will get to a point where you would find it extremely awkward and shameful to use such language, even if you wanted to. Once people know you as "that guy who never swears", there will be an expectation on you to live up to that image, which will make it easier.