The seventh anniversary special of Running Man invited members' families. Kim Jong Kook invited his brother, who is a plastic surgeon and doesn't exercise at ordinary times. Therefore, his brother said that Kim Jong Kook was a "mother bear" in the program, because he nagged himself at home all day like his mother, so he should pay attention to strengthening his exercise. So when fitness becomes a demon, he will keep persuading others to exercise because of them.
In addition, Kim Jong Kook was a health missionary. He not only loves fitness, but also is very picky about his diet. He doesn't drink carbonated drinks or eat fried food. Even Lamian Noodles, Fried Rice Cake and Zhajiang Noodles, which are very popular in Korea, he seldom touches them, because he doesn't want his fitness performance to be affected by his diet. Therefore, people who become obsessed with fitness are very picky about their diet.