Proving you can balance indulgence with healthy living, Greek island escape F Zeen is a breath of fresh air, says Jemma Crew.

As I set up my mat between ancient trees that poke through the circular wooden Armonia yoga deck - which means harmony in Greek - my lungs are grateful for the fresh mountain, forest and sea air.

I perform sun salutations while birds chirp away in the treetops above, and waves end their journey with a soft crash on the shore below. I'm watched solemnly by one of around a dozen adopted cats that roam F Zeen resort.

Hidden away on an Ionian hillside, in the shadow of Mount Ainos, nestled into sloping forest that rolls down onto Lourdas seafront, this adult-only wellness retreat enjoys the best of Kefalonia's bewitching landscapes.

Why is Kefalonia a recharge retreat?

Kefalonia - the largest of the cluster of Ionian Islands dotted along the west coast of the Greek mainland - is also one of the least densely populated.

It is incredibly green and lush, with Mount Ainos - the dramatic backdrop that towers above F Zeen - classified as the only national park on a Greek island.

An earthquake in 1953 caused widespread damage to the island, leaving 90% of its buildings in pieces and causing many islanders to flee.

The Kefalonia that was rebuilt from the rubble is equal parts charm and tradition, and relatively unspoilt compared to more developed Greek islands popular with Europe's younger crowd.

What's the F Zeen story?

F Zeen was a term in ancient Greek used to sum up 'the good life', and the resort does everything it can to promote an ethos where, as Hippocrates said, "everything in excess is opposed to nature".

Open for its first full season in 2016, it's truly a family affair, with mother, father, sons and daughter all involved in the day-to-day running.

Matriarch Suzanne Koumoudos, who with her Greek husband Dennis owns a sprawling collection of luxury Kefalonian villas, tells me that food has always been a huge family passion, and that when they went on holiday, they were always looking for a hotel with a gym, so they could indulge.

And so the idea for F Zeen was born, set in the midst of 20 acres of cypress, eucalyptus and pine trees, that have been in the family for hundreds of years.

With pared back yet luxurious nature-inspired rooms, three freshwater swimming pools, Jacuzzis, a spa, daily group gym and yoga classes, it's an inspiring place to slow down and reconnect with yourself.

Do you need to be a yoga bunny to enjoy the space?

Yoga teacher Anastasia Koumoudos gently guides groups through a series of rejuvenating and relaxing poses, but guests can use the equipment whenever they like. For the more adventurous, aerial yoga sessions can be arranged.

A split-level outdoor gym - complete with cardio machines, free weights, personal training sessions and a sublime sea view - is also available.

Steps away from the retreat at F Zeen's on-the-beach activity hub, guests can take out paddleboards and kayaks for no extra cost. They can also borrow bikes and maps of local hikes.

What's the spa like?

The spa uses organic seaweed from the Irish Sea, sourced by the family-run company Voya.

A small team of therapists use hand-harvested leaves in treatments, including baths, massages, masks and wraps for their antioxidant and anti-ageing properties.

My city-polluted skin is treated to a detoxifying Anti-ageing Restorative Facial (E90/£79) which I enjoy, notwithstanding the pungent marine aroma which assails my nostrils as strips of slimy seaweed are slathered on to my neck and chest.

For sun-scorched skin a must-try is the spa's After Sun Oasis (E50/£44) - a heady mix of lavender, aloe vera and avocado oil, forming a perfect soothing combination to calm and nourish.

What's the food like?

F Zeen now boasts two restaurants which offer healthy Greek dishes with a modern twist, using recipes passed down by the Koumoudos family's grandmother.

Many of the herbs used in dishes and the impressive range of teas are grown on site, and vegetarian and vegan-friendly menus are guided by the seasons.

Breakfast can be enjoyed at Gaia restaurant, where dining tables overlooking the Ionian Sea are decorated with stray petals from a shocking pink ceiling of bougainvillea, through which shards of sunlight stream, while the new Selini restaurant is open all day.

But the real stars here are the drinks: Dozens of wellness teas; zingy green juices; smoothies as far from the pureed sugary pulp found in supermarkets as you can get; and alcohol-free health shots which pack a hefty punch to the gut and kickstart a sluggish digestive system.

Can you sleep in perfect harmony?

Don't think you'll be away from nature once you head to bed. The calming rooms feature neutral furnishings; some boast spacious private balconies, while newer rooms have their own Jacuzzi.

The new 'Raw' wing, due to open in 2018, will almost double the Greek island resort's size - making 53 rooms in total.

What else is there to do?

Kefalonia is famed for its honey, and a trip to the nearby Dias Apiary (E16/£14) - a 20-minute drive from the retreat - proves to be an unexpected delight.

I don a head-to-toe white bee suit with trepidation as I approach the ever-increasing hum from the darkened inside of one of dozens of sealed wooden boxes.

We hear fascinating anecdotes about the winged creatures 'dancing' and even, after much direction from our patient guide, manage to identify the queen - the largest of the insects.

We are shown how to extract honey from the hives, before tasting the wax, royal jelly, propolis (a mixture of bee saliva and beeswax) and pollen.

After drinks and a selection of dripping honey cakes and sesame treats, I make a beeswax candle to take away as a souvenir.

If bees aren't your thing, a plethora of other activities are on offer. The ruins of the Sissia monastery are just over a 30-minute walk away. The monastery, which was destroyed in the earthquake, is believed to have been founded by St Francis of Assisi in the 13th century.

How to get there

Rooms cost from E180/£158 per night on a B&B basis; Raw Wing rooms from E209/£184 per night on a B&B basis. Visit fzeenretreat.com

British Airways (britishairways.com) is launching direct summer-only flights to Kefalonia from London Gatwick on Tuesdays and Saturdays, between May 15 and October 6, with return fares starting from £118.