On one of the recently-aired episodes of KBS' talk show 'Happy Together 4', Yang Chi-seung made a guest appearance.
In this episode, Yang Chi-seung mentioned that he is currently working with the members of 2PM, Kim Woo Bin, Sung Hoon, JIN and many other celebrities.

Yang Chi-seung said, "I have nothing bad to say about JIN at all. He does everything that I ask him to do without making any complaints. Some people would complain a lot, but JIN never has."

The personal trainer added that JIN always says goodbye to him with a bright smile when he leaves the gym as well.
Upon hearing this, the hosts and other guests raised their thumbs up for JIN and said, "Wow, JIN. What a great guy you are!"

(SBS Star)