To me it sounds like someone is getting out of a situation without any damage or trouble to themselves, or even having gained an advantage from the situation. For example a director of a company may get out of the company in good shape if he gets a big bonus when he leaves.

Are you sure the sentence was not "You're getting out of good shape." ? "getting" = becoming "out of" = [a sort of negative] / [away from] "good shape" = fit, thin "You are getting out of good shape" = You are becoming fat. [presumably by not taking enough exercise].