Courteney Cox looks divine at 59! In an Instagram video posted on Monday, February 5, the Friends actress showed off her flattering physique while standing on an outdoor deck, where she was preparing to do a cold plunge. In the clip, Cox sported a purple triangle bikini and spoke to the camera while pointing out her thick, thermal-like ankle socks she comically wore with her bathing suit. “Is this cheating? ‘Cause your feet get really f—— cold,” the Scream star quipped, as she had one of her legs propped up on the side of what appeared to be an ice bath. The brunette bombshell had her hair…