As these photos show, the trim and toned 37-year-old actress looks just perfect in her skimpy black two-piece.
But the Million Dollar Baby star has more than good genes to thank for her alluring poolside display.
Fighting fit: Hilary Swank stands proud in a skimpy black bikini, spotted soaking up the sun while on holiday in the stunning Hawaiian island of Kauai yesterday
The two-time Oscar winning star is pictured here on the idyllic Hawaiian island of Kauai with her long-time agent boyfriend John Campisi.
However, when not soaking up the sun on holiday, the Los Angeles-based actress works hard at maintaining her enviable shape with rigorous daily work out sessions.
With steely dedication to her fitness regime, early bird Hilary is up at the crack of dawn most days and heads to Equinox Fitness in Santa Monica for an hour-long workout.
Wearing a form-fitting ensemble, she will often meet with her personal trainer for a punishing session, including a mix of boxing and sparring and free weights.
Toned, tanned and trim: The 37-year-old actress owes her incredible figure to punishing daily workout sessions at the gym
'She is also a big fan of the spin class,' one fellow gym-goer tells MailOnline.
Our source added: 'Hilary just looks incredible. She is tiny and so toned.
'Everyone looks at her with these envious eyes, but when it comes to her exercise she is not one to hold back.
'You'd never catch her reading a magazine while half-heartedly peddling on the cross-trainer. She goes for it full throttle.'
Hand in hand: The Million Dollar Baby star is on vacation with her long-term boyfriend John Campisi
