My mom always tries to make this argument to me. "All that muscle is going to turn to fat one day, Ferret." (I'm not even overly muscular, just lean and she knows I lift) "I know people who have had that happen!" Yeah, because your friends all started to let themselves turn into bovines when they were in their 40's, doesn't mean that I'm gonna let that happen to me. I usually just reply with, "that's not how it works. That's not how it works at all," and she leaves me alone until the next time.