So THAT’S her secret! How Britney’s achieving her killer summer body

Tanned, toned and smiling – yup, we reckon Britney Spears' image overhaul is just about complete.

The singer has been working hard on her figure over the last couple of years, and while her steady weight loss and increased muscle tone has been clearly visible for a while now, it's her latest Instagram snaps that really hadve us taking notice.

Just weeks after sharing two "mini music videos" showing her dancing in a black two-piece, the mum of two posted some altogether more relaxed photos yesterday – and there was no hiding those abs.

One such photo shows Brit standing on a golf course with her "little munchkins" – her niece Lexie and nine-year-old son Jayden. Wearing a pink crop top and bright blue shorts, the singer looks tanned, athletic and – most importantly – happy.

So what's Britney's workout secret? Well, there's no quick fix it seems. According to the woman herself, it's all about hard work.

The singer combines short, high-intensity workouts with cardio classes and – of course – high-octane dance rehearsals when she's working.

"I like my workouts to be effective in a short amount of time. I start with 20 minutes of intense cardio – usually running -move on to light free weights, body-weight exercises such as pushups, squats, and sit-ups, then finish it off with a stretch," the singer told Women's Health last year.

Often the mum combines two workouts in one day – going for forty laps in the pool after a Totally Drenched class at her local gym, Drenched Fitness.

"I love this class. It's high-energy and combines treadmill work with circuit training. Being in a group setting pushes me to work harder," she says.