With her long, lean legs and toned abs, Millie Mackintosh has the kind of body most of us can only dream of.

[Read more: Meet Millie Mackintosh's favourite nutritionist Madeleine Shaw]

And boy does she work for it. The former Made in Chelsea star is naturally on the slighter side but Millie is the sort of Instagrammer you’re just as likely to see sweating at a fitness class as you are flaunting her figure on a beach - and that includes while on holiday with new fiance Hugo Taylor, who she recently got engaged to.

Since she’s pretty much top of our #bodygoals chart, we thought it was high time we found out how we get in shape like Millie. Or at least try to.

Personal trainer Olivia Cooney, whose roster includes Millie herself, says: “If you are just introducing fitness into your lifestyle or ‘starting over’ post-baby or after an injury, the key to success lies in doing effective exercise but at your own pace.”

Here, she’s shared the three workouts she and her clients swear by.

Workout no.1: Walking

“Walking is a great form of exercise that everyone can do, and the longer you walk, and more effort you put in, the more calories you’ll burn,” explains Olivia.

“Harvard researchers have shown that a brisk one-hour walk every day will also slow down 32 different genes which promote obesity while studies at Exeter University found a 15-minute walk helps curb cravings for chocolate.”

The moves: If you’ve been quite inactive, start with three 10-minute walks a day and gradually increase your pace and time until you can walk at a brisk pace for at least 30 minutes without feeling uncomfortably out of breath.

If you are already fairly active, work towards a three- or four-mile walk every day, which will burn around 400 calories.

Turn it up: “Walking is not just about the distance you cover. For maximum results, it’s also important to maintain a brisk pace and keep your heart rate up. If you can already manage a brisk one-hour walk, try adding some power pit-stops.

“You could also use the bench for press-ups, tricep dips, side step ups and landing in a side lunge. Adding these short bursts of energy along your walk will transform the level of your workouts.”

Workout no.2: HIIT

“High intensity interval training is all about fast-paced workouts that torch calories in a fraction of the time, so there is no need to spend hours in the gym — praise the lord,” says Olivia.

[Read more: What exactly is HIIT training?]

“The beauty of timed workouts is that you set your own pace. Just make sure it challenges you. HIIT should be as intense as you can make it.”

The moves: Beginners should do this for 20 minutes, performing three rounds of each with 45 seconds of activity followed by 15 seconds of rest:

• Jumping jacks
• Mountain climbers
• Jumping squats
• Bicycle crunches
• Tricep dips (on a bench)

Turn it up: If you’re more advanced, or when you’ve mastered the beginner’s moves, move onto three rounds of these, each with 45 seconds of activity followed by 15 seconds of rest:

• Burpee
• Press-ups
• Ice skaters (lateral side jumps)
• Crossed mountain climbers (opposite knee to elbow)
• Jumping lunges
• Tricep dips (on a bench)
• Plank, jumping legs out laterally

Workout no.3: Boxing

This is one way to de-stress while you burn calories.Olivia recommends teaming up with a boxing buddy if you can but if not, shadow boxing (where you’re boxing an imaginary opponent) works as well.

 

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The moves: Grab two pairs of boxing gloves or one pair of gloves and a pair of pads and head for the park.

One person holds up their gloves or pads and the other cross-punches with the basic jab at a regular ‘one, two, one, two’ rhythm for as long as they can. When the puncher needs a rest, allow 30 to 60 seconds to fully recover before doing a second round.

Add in cross punches with the basic jab at a fast pace for four rounds of 25 punches, with a short 10-second rest between each round. After four rounds, swap over.

[Read more: Boxing for beginners: 7 reasons why you should start packing a punch for your health]

“Aim for speed and intensity as these short sharp bursts elevate the heart rate even more than the rhythmic punches of the spar starter,” adds Olivia.

Turn it up: Olivia recommends adding body-weight exercises into the mix. Her favourites are: 25 jab cross punches followed by four burpees —try this for three rounds; or 25 upper cut punches followed by 10 full sit-ups, for three rounds; or 25 hook punches followed by 10 press-ups, for three rounds.