Ill... AGAIN!

Once again, I am ill. I honestly don't know what's wrong with my immune system - I consider myself super healthy yet I am always picking up bugs. It's another cold this time. I guess that's what you get when you are always outside with the horses!
Does anyone else get as sick as often as this? I know a lot of people soldier on and keep riding, but who bites the bullet and has a complete day off to save days of suffering? I always feel so guilty if I ever decide to stay home, but when my mother is here I'm forced to follow her good, motherly advice. I'm sure the horses don't mind an extra day off!