Constant Crud

My daughter has been sick on and off for 2 weeks now. It is now down to a hacking cough and runny nose. This morning my son woke up with the same symptoms and I have cold symptoms and a sore throat. My kids used to NEVER get sick. Then in April I started going to the gym. The kids play in a child watch for an hour 5 days a week and now it seems they are always sick. I'm hesitant to give that up because a) I'm losing weight and b) it's the one thing I consistently do for myself. I need it for my mental and physical health. Is it a fair trade off? I'm not sure.