Of course, the physical benefits are thrilling, but the mental rewards you reap are even greater," says Nitta, head trainer and owner of a bustling Tokyo kickboxing gym.
"I started martial arts because I wanted to do something about the feelings of self-loathing and shame.
Martial arts taught me many valuable life lessons."
"Martial arts aren't just for tough, macho guys.
GQ Japan editor-in-chief Masafumi Suzuki, 70, is a loyal kickboxing devotee who has been a member of a Nitta gym for about 15 years.