Admit it: 48 never looked this good! The Aussie model, known around the world as "The Body," ignited bikini envy from a whole new generation of beachgoers when she flaunted her fit form in the pages of PEOPLE. "I do get jitters," says Macpherson of donning a two-piece 20-plus years after gracing four Sports Illustrated covers. "I was comfortable [at the shoot]. But I had to get my self-conscious 'maybe I don't look my best' head out of the way and go with, 'Let's celebrate where I'm at.'"