Daughter in daycare; I'm always sick!?

My 15 month old is in daycare full-time, and I totally understand that she is new to the world and developing her immunities, thus get sick often...but WHY do I get each virus she brings home? Shouldn't my immune system at 33 be more complete by now? Of course, she shares her food (and sloppy fingers) with me...but I'm generally healthy, take my vitamins, get 7 hours sleep each night...Where's my immune system at?