Especially because those younger kids don't even think about it. Getting beat up a bit is the entire point of going to class in Muay Thai. If you're not getting beat up you're not progressing, and if you're not progressing then you should be moving towards doing so.

Everyone has been beaten up by someone younger/smaller/weaker than them in the sport. It's a rite of passage and is a large reason why the sport is filled with humility and discipline. There's always someone better than you, and it's extremely important to keep that in mind especially when working with those who have less experience.

I started when I was 14 and after 6 months of working my ass off to become proficient enough to spar for the first time, a girl half my size made it very apparent I had 0 clue what I was doing. I'm 24 now and I still get regular, similarly grounding reminders. A few weeks ago I trained with someone who made me feel like I was still learning to jab, and I learned more from them in one class than I had in the prior few weeks.