Editor Susannah Taylor is training for a Sprint Triathlon, and is currently questioning her sanity

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I’ve only gone and signed up for a sprint triathlon. It seemed like a good idea at the time. My friends and I thought it would be really clever to do the longer distance (last year we did the Super Sprint which is shorter.) So here I am, signed up for a 750m swim, 19.8km bike ride and a 5.5km run in early June.

While it’s a beautiful setting in Blenheim Palace grounds, the reality is this: the swim is in a cold, murky green lake (you can barely see your hand in front of your face in the water), I will undoubtedly get kicked, I will probably choke at some point due to so many people thrashing about in the water, I don’t really like running (an issue, I know), I have a fear of breathing in water (it's not natural to dunk your face in an out of water and trying to breath in and out at the same time), I have a dodgy knee, and last but not least it’s skin-tight Lycra and wetsuits all the way. Yep, I am questioning my sanity, big time.

Although, in a very weird, jittery-nervous-laughter sort of way, somewhere in the depths of my tummy there’s also a flutter of excitement. I’m a believer that fitness should be fun and exhilarating - the idea of endlessly pounding a pavement training for a marathon (while totally admirable) is not for me, but doing something a bit crazy like donning a wetsuit, swimming in a lake, ripping the wetsuit off to reveal a tri-suit underneath, jumping on a bike for three laps of beautiful Blenheim Palace grounds before running (or limping) around it for the final two laps is all a bit nuts, but in a way it's brilliantly sort of nuts.

If you’ve never pushed yourself well out of your comfort zone, and felt the immense sense of achievement and empowerment this brings, then a triathlon is one hell of a way to do it. No wonder triathlons continue to be the fastest growing group participation sport in the UK, and by the way, women are the biggest growing section of all.

So with four weeks to go, I’m currently tri-ing hard. No, let me re-phrase that - I’m trying to cram in bits of training around my mentally busy job, a commute from Oxfordshire to London, my two children and some sort of social life. The social life bit is actually the toughest - I’ve realised I can’t go out and drink a load of wine with my friends and then expect to power up some hills the next morning without wanting to be sick. Problem is, though, that my willpower is quite weak – last weekend I offered to drive my friends to a very swish pub called the Wild Rabbit in the Cotswolds near where I live. My resolve lasted all of 10 minutes before I was tempted by some pale, crisp, cool rose wine and called my husband to tell him I was booking a taxi home. I would like to say I won't drink one more alcoholic drink between now and race day but I don't know if I can promise that!

So what does training for a triathlon look like? Well, as well as boxing and doing strengthening work, and sprinting horrible, terrifying treadmill sprints with my trusty trainer  Steve Mellor of Freedom2Train , I’m trying to fit in a run session, an hour’s biking and a swim every week too. That’s five days of exercise a week, and if you think that’s a lot, according to the excellent new book ‘Run, Ride, Sink or Swim’ by fellow triathlete and journalist Lucy Fry (a must-read for anyone embarking on this bonkers but briliant journey), apparently many triathletes exercise twice a day (good God).

Which sport of the three do I find the most challenging? It changes, but right now it's running. Two years ago I had a big knee injury – I snapped my left ACL skiing (a key ligament that prevents the bottom and top of your leg sliding in different directions), and while it feels ok now, I have to be very careful not to overdo things too early or risk injury. Instead of heading out and running the full distance, Steve has set me sprints to do to increase my fitness levels fast, so once a week I take myself off down to the nearest country lane and run in fast, exhausting intervals with breaks in between. I won’t lie, it’s awful, it feels like your lungs can’t take in any more air or your feet won’t go one more step, but boy does it make you feel good afterwards (and I know I’m much fitter for it.)

I’ve also just started doing Brick sessions. This doesn’t involve carrying bricks in your pockets, or a backpack full of them (that might actually be quite fun), nope, this is where you go for a hard cycle, jump off your bike and go straight into running. The change of movement from bike to ground creates a horrendous lead or jelly-like feeling in your legs and feet – something all triathletes have to get used to.

What else am I doing? Well I’m rolling my muscles with a deadly foam roller covered with nodules that sometimes makes me scream in pain - it's like a deep tissue massage intensified by one hundred. This is essential for keeping my muscles from seizing up or pulling my knee out of line. I’m also packing in a lot of sweet potato, butternut squash and chicken, as well as smoothies laced with Maca powder (a superfood energy-giving powder) and protein to help me refuel. I am, it seems, starving all the time.

What am I failing at miserably? Apart from abstaining from alcohol, I’m also not sleeping very well – I keep waking up in the night and as a result I’m feeling quite exhausted. I need to start getting more shut-eye (mission for this week). I’m also not drinking enough water (one big downfall of mine).

As for the swimming (most novice triathletes' biggest fear), I’ve been swimming 50 lengths of front crawl at a time in my local gym pool. Now this may sound impressive but it’s one thing being able to sport a bikini in nice warm water and then have a relaxing sauna, but it's quite another being squeezed into a wetsuit and swimming cap combo and being submerged in a freezing cold lake. I know that physically I can swim the distance, but it’s my mind, not my body I need to get a grip of. If you’ve ever swum right out to sea you’ll know what it feels like to be far from land and not being able to touch the bottom. I had some swimming lessons last year which I found incredibly helpful, and next week I’m off for another with a swim trainer at the super swanky Bulgari gym in Knightsbridge.

This weekend, however, as you lie in bed on Saturday in your cosy PJs under your lovely soft sheets, spare a thought for me at 8am when I’ll be donning a wetsuit and plunging into a freezing cold lake somewhere near Oxford to practise open water swimming. I'm terrified but that quiver of crazy excitement is still there… I will keep you posted.

Susannah's top tri-hard essentials:

A wetsuit - You will need a wetsuit for swimming in lakes and outdoor pools. It's best to go for one that's made of thinner material so you can move well. Try this Zone3 Venture wetsuit  which available at Wiggle.co.uk.

Goggles - Not any old goggle will do. I will never go back to smaller framed goggles having worn these Aquasphere Vista o nes. They have big lenses that have a much wider vision and don't dig in or leave groove marks around your eyes for hours afterwards (important!).

Run, Ride, Sink or Swim by Lucy Fry  - I am seriously enjoying nodding along to this very honest and funny account of personal trainer and journalist Lucy Fry's year of triathlons.  A reassuring must-read for anyone embarking on becoming a tri-hard.

A road bike - a road bike  is a lighter bike with low handles and thin wheels that is speedy, and you can be more agile on it. Make sure you go for a frame that suits your own.

A tri-suit  - On race day you will wear a wetsuit and underneath you'll need a tri-suit. They are generally made of quick-drying fabric so you can comfortably move onto the cycling section of the triathlon. The shorts area is normally padded to help protect your privates from getting bashed about!

A swimming costume - you'll need a good swimsuit or bikini to power through the water when you're practising. I have my eye on this Free Dive Swimsuit from Sweaty Betty

A good physio, and training advice - when you enter an endurance sport such as a triathlon, you increase the likelihood of injury. If you do get injured, I cannot recommend Isokinetic  enough. They are an amazing sports rehabilitation company who helped rehab me back to strength post knee operation (they found me a top knee surgeon too). Without these guys and the continuous support, help and wise training advice from Steve Mellor from Freedom2Train I wouldn't feel as strong as I do or be training for this nutty race.

Follow Susannah at  @STaylorGTG