We are all baalei Teshuva and we all do teshuva every single day as we all have opportunities at every given moment to do so. So yes we can change and we can re-sensitize ourselves if we CHOOSE to do so.
WE can choose to not infect our ears with foul language. We CAN choose to not infect our sensitivities with off color jokes or even mother-in-law or wife jokes for that matter. WE can choose to turn off the TV (or throw it out), turn off the video, computer, cell phone, etc. We can choose to throw out the magazines, newspapers, books, etc or monitor what comes into the house including the radio AND we can choose to say to others when we are out of the house “I would appreciate if you would refrain from that language when we are together”. If you frequent a store where the workers are foul mouthed or dress too “slack” speak to the owners, you can always find another store.
As far as speaking to the other gender or addressing them as Mr. or Mrs., it is not always possible or appropriate to maintain that kind of distance. If everyone in your office is informal and called by their first name and you especially are the youngest person there, you would look like an absolute uncooperative snob to insist you be addressed formally. Of course you may set other important boundaries regarding religious issurim and sensitivity issues, but the formality issue is something you might have to compromise on.