I finally have proof that though I can teach fourteen hours of fitness a week, for twelve weeks straight, and never miss work, I often get sick when I stop!  Many fitness instructors I know have experienced the same thing. Many people get sick in the middle of vacation and feel cheated.
According to Marc Schoen, PHD and author of “When Relaxation is Hazardous to Your Health,”a phenomenon called, the “Let Down Effect” can result in us getting sick once we eliminate the stress of work or a big project.
When we are under stress, our body is equipped to fight for survival but if we come to a screeching halt, and drop onto the couch for days, Dr. Schoen claims that this can “lead to biochemical changes that can result in a weakened immunity.” (http://marcschoen.com/the-let-down-effect/)
I am happy to say that I have been quite healthy this summer because I kept five classes running, but even this small change, resulted in a calf injury. I stopped my daily routine of stretching because I was not longer teaching yoga everyday.
The best advice that I can give to avoid getting ill on vacation, is to keep doing a small portion of your fitness routine daily or weekly. It is so tempting to give in to our desire to do absolutely.
Many of my students continue to walk and stretch when they are cruises or tropical beach vacations. 
When I know that you are leaving on vacation for a few weeks, I tell you to walk and stretch daily and then I did not follow my own advice!
I look forward to getting back to our workout schedule in September but until then, lets keep active together.
See you tomorrow,
Beth