What do you do when people don't return blu rays/ dvds they borrow from you?

[James_Younger_Gang]

I know that there is a thread asking if you loan dvds or blu rays to people. But I am asking: To what extremes do you go to recover the movies that you lend out to others if they forget to or simply won't return them? Do you harass them? Do you forget about the movie? Do you appear at their place? Do you get pissed off and swear to never lend a movie again ever?