You tell us.
Because, regardless of the circumstance, you demonstrated/admitted that even a supposedly mature guy your age can still be irresponsible. The kids are obviously wrong but you are asking for responsible behaviour from teens when even adults have a hard time with it. And you say you accept responsibility, but the fact you do nothing about it belies that admission. Instead it was, "Oh, it's hard to lose weight when you get to a certain age." I suspect that I am older than you yet I have very gradually lost about 60 pounds in the last 8-10 years. You're right. It's not easy. It's damn frustrating. But saying you are too old is a cop out, i.e. shirking responsibility, STILL.
My point is, don't be so high and mighty judging (stupid) teens and their irresponsibility, when it is has always been their nature and when you are guilty of the same. Irresponsible is irresponsible whether it is virus or personal health. And on top of that, you stupidly try to politicize it by blaming it on the teachers and by inference left-leaning people who were supporting the teachers. You failed on so many levels.
p.s. I am not at all concerned about your knees. It is your hypocrisy that got my attention.