Why do I never get sick?

Hi!

Before I begin, I'd like to say that in NO way am I bragging about this or complaining. I'm just curious :)

So, I'm still in school, around sick kids all day, and have a regular life. I eat healthy but not like the veggies-for-breakfast kind of healthy

(Not that there's anything wrong with that:D)

I dance and take acting lessons, sometimes play soccer with friends, I don't go to the gym or anything

I don't sleep NEARLY enough (like 6-7 hours) 0_o

The only vitamins I take are collagen for my incredibly weak nails

My house isn't disinfected, I have 2 dogs, 2 cats, 2 fish

AND I also have no allergies, have never broken anything, and never hurt myself BUT I make up for it because I am constantly embarrassing myself socially :(

Just wondering if I have something wrong with me or if it's just my immune system…I NEVER get sick, even colds

All my friends say I'm gonna be one of those people who live to 100 which i doubt ;)

Thanks in advance and detailed answers please :D