Can a 46-year-old mum of four, who has only been on a bike six times in 10 years and last wore a swimming costume four years ago, do a triathlon? It's not a trick question. I have nine weeks to prepare for my first ever sprint triathlon at Leukaemia & Lymphoma Research Blenheim Palace in June.

The family dog, a water-phobic blind Airedale Terrier, may be better qualified for this than me, but I'm determined to take part.

So what has got me off the sofa and into a wetsuit?

First I’ll tell you what it’s not:

It’s not a quest to be super fit, compete in races or rack up a series of personal bests (whatever they are).
It’s not because the kids are threatening to enter me for their favourite TV programme Ninja Warrior: a humiliating Total Wipeout-style Saturday night sport show.
It’s not because I want a butt like would-be athlete Pippa Middleton (though that would be nice).

The reason I have signed up to a triathlon is because I’m a bit lazy. But I want to be fit so I have the energy to play with my younger children (especially the four-year-old) and be a good role model for my elder three, aged eight, 11 and 12.

I’m more inclined to stay in and drink wine watching Breaking Bad than go out and sweat my socks off. I need motivation and a goal – I like to be part of a team. So, Blenheim, here I come. Five members of the @ELLEfitteam are joining me for the 750m swim in the lake, the 19.8km ‘undulating’ bike ride and 5.7km run.

I love running (well, jogging), which I took up two years ago, but I will never do a marathon (too boring). A triathlon looks like it’ll be fun though…

And I’ve lined up super trainer Tim Weeks, a former Olympic triathlete, as well as triathlete Marsha Al Hage of RGActive, and Olympic swim coach Dan Bullock to help me. Surely they can get me through? Plus I met Victoria Pendleton once so maybe the cycling magic has rubbed off. What’s the worse that can happen? Follow this blog and you’ll find out.

WEEK ONE

During the Easter holiday, I managed 20 lengths in the pool, two surf lessons and a 35-minute 5k run: this does not a budding triathlete make. I did however read Born To Run by Christopher McDougall. The New York Times bestseller. I felt fitter after each page.

Triathalon Session One: Tim Weeks takes me on a 45-minute ‘de-scampering’ session. For nine weeks, I have been inactive, waiting for a stress fracture in my shin bone to heal, undoubtedly caused by weak ankles and a wobbly running style. It’s time to ‘activate my glutes’ he says after a long talk about body biometrics. He is a very patient man who believes sport should fit into, rather than run, your life.

I wonder if my secret skills of rollerblading and skipping will come in handy here. They do – he says – but it’s 30 minutes of squat-type exercises first. Then we slowly run up my nemesis, Primrose Hill. A six-year-old boy passes me at speed. I am now officially anxious about the triathlon. I consider asking the ELLE art team to make me a badge: ‘I am doing a triathlon. Be nice to me’.

My children cannot stop laughing. This is going to be harder than I thought.

1. Marsha El Hage 2. Our RGA Active 8 Week Training plan 3. What the professionals use to skip with

WEEK TWO

I am on a Boris bike in London’s Regent’s Park as I don’t own my own yet. After 10 minutes of fast pedaling, Tim asks me to leap off and run for 2km. Something has happened to my legs. No matter how relieved I am to get off the bike, they won’t move. It’s the oddest feeling. This is a Bric (bike-run-bike) session. I don’t like it. Again I think: ‘This is going to be much harder than I thought.’

Marsha Al Hage comes to ELLE to show us our RGActive Blueseventy trisuits, which we wear under our open water wetsuits.

She talks of holding on to a tree when you get out of the lake and stripping off your suit. I feel faint. And notice the tri-suit has a padded gusset – I hope it isn’t just mine.

I head off to the local pool for a swim. I manage four lengths front crawl before realising I’m going to need to start this front crawl business from scratch. I email Marsha in a panic. She assures me it will get easier, tells me not to panic, and a session at Hampstead Heath ponds is arranged.

Two things I now know:

1) Swim fit is much harder than run fit. Much more aerobic.

2) An open-water wetsuit is twice as tight as a seawater wetsuit (which, growing up in Cornwall, I am used to). You can see your organs through it.

I take up Garuda Pilates once a week to ‘tie’ my dodgy body together. Marta the teacher uses a Reformer machine to ensure your muscles link through your core area. That way, the glutes will activate and give me the right strength to run correctly without pain and with more power. This is the most enjoyable part of training so far. I feel like I'm being rebuilt and stretched thoroughly after the session.

To conclude: I can’t really swim. I don’t have a bike yet and my butt doesn’t work. This is going to be much harder than I thought.

4. George Stoy is Cornwall's top sruf instructor 5. When the @ELLEFitTeam ran the Paris Half Marathon in 2014

MARATHON SUNDAY APRIL 24

In an attempt to inspire me into achieving this triathlon and not giving up (because by now I am close to that) Tim takes me to the VIP marathon breakfast with Kenyan running legend Lornah Kiplagat who earlier in the week had taken the @ELLEfitteam on our weekly run.  

‘Everything should be fun,’ Lornah tells me. ‘Just go to the start line and see what happens,’ she advises. She urges me to take the competitive nature out of my thinking, to relax, to just take part. I can stay on a bike, stay afloat and I can run 5km. That’s all I need to know.

Then I watch Paula Radclifffe, the fastest female marathon runner of all time finish only yards in front of my seat. I can see the emotion in her face. After she powers thorough the ribbon she tweets ‘I run because I love running, I love running because I run’. It’s so inspiring to see. I realise it’s worth persevering. That evening I swim 30 lengths, painfully, slowly but I did it.

7. Super-trainer Tim Weeks and Minister for Sport Helen Grant 8. On the Starting Line with Paula Radcliffe at We Own the Night 2013

THIS WEEK I HAVE BEEN

Listening to King by Years & Years. Testing swimming hats; none of them are stylish. Over to you Henry Holland! Wondering where all my matching sports sock have gone. Hand them back. No questions asked! Eating quinoa with kale - it maybe helping.