Kourtney Kardashian Photoshoot For Us Mag

Kourtney Kardashian was looking more fit and toned than ever in micro-mini shorts and a sports bra top in Malibu on Thursday.

In photos exclusive to UsMagazine.com the reality star and mom, 31, showed off her gym-perfected bod -- jogging and doing step-ups beachside -- as she shot pics for a fitness book.