A woman follows along with an instructor during a Zumba class at the Marine Corps Exchange aboard Marine Corps Base Camp Lejeune, May 25. Semper Fit held a variety of classes at the MCX during it's Health and Fitness Week. - A woman follows along with an instructor during a Zumba class at the Marine Corps Exchange aboard Marine Corps Base Camp Lejeune, May 25. Semper Fit held a variety of classes at the MCX during it's Health and Fitness Week.