I think the key to change is wanting to change.  Yes it is a habit and if we think it is a bad habit then it is worth the effort to rid ourselves of the habit.

My dad never used foul language.  I spent a couple years in the service and a couple years as a diesel mechanic and foul language "seemed" necessary to fit in, or even to top everyone else.  If I could out cuss the truck driver then my opinion mattered.

I believe it really is a crutch to try to gain "respect" of co workers, actually a crutch to make us feel secure because we really are insecure.  I hear the most foul language from those who appear to be insecure and trying to prove they are something.  And as with all crutches, it becomes a habit difficult to break.

Some note bringing religion into the discussion.  I think we all have religion, just many are not Christians trying to follow strick guidelines.  With the help of Christian friends, prayer and time, I don't worry about ever "slipping" with a foul outburst.  It basically just isn't in me any longer.  Oh I get angry and blow up occasionally but I never accidently use foul language.  Sadly though, if I get angry enough I have on occasion deliberately used foul language for effect, to emphasize my displeasure with an individual . . . that old insecurity trying to run my life, but I'm not proud of that behavior.  The high road is less travelled, but always the best.