Yodsanklai is a scary dude. He’s a Muay Thai fighter (not a kick boxer, but sometimes Thai fighters will do a kickboxing match for money/ exposure/ etc). No surprise, professional Thai fighters also do an insane amount of running and calisthenics. A lot of those guys are very strong for their size, but they’re tiny. For some, it is a way out of poverty. Lots of Thai kids train from a very young age, but I’m sure it’s a very small percentage who make it to the big stadiums.