On the Ball Core Training

A serene and friendly wellness resort just two hours outside Los Angeles, Oaks at Ojai offers all sorts of specialty programming throughout the year. Its On the Ball week (May 20-24) is the toughest offering on the spring calendar -- as those who have done even a standard hour on the stability ball know. It tests one's balance, core strength, and hundreds of tiny muscles you don't even realize you have -- 50 minutes wipes out most people. Five days is only for those with champion willpower.

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Lena Katz is the senior travel correspondent for JustLuxe, covering trends, tastemakers, news and more.