My heart is pounding, my breathing is ragged and the muscles in my arms burn as I lower myself into a push-up position from a drop down squat for what feels like the millionth time in a row. To my horror I suddenly feel a hand firmly pushing me further down to the ground and a woman's voice yelling that I need to get even lower. My rage at the injustice and impossibility of the task is only exceeded by the feeling of my spirit being crushed and my urgent need to collapse.
Welcome to boot camp.
Like most neurotic women obsessed with losing inches and dropping those last few pounds, I'm no stranger to fad diets and fitness crazes. I've tried juicing, fasting, supplements, low-carb diet regimes. Smartphone apps for food diaries, running and weight training. Personal training, pedometers and downloads of the latest gym workouts promising to turn you into Jessica Alba within three days. A lot of money, time and tears later, I'm still not the toned and athletic body shape that I've long dreamed of. So I've decided to junk in the fads and get serious with my fitness regime.
Watch: Bikini Fit in Hong Kong
It's only day one of Bikini Fit , a female-only fitness group that is making waves in Hong Kong with its "body transformation programmes" that focus on physical training, support and education on nutrition and lifestyle. And I'm almost regretting my decision to plunge headfirst into a six sessions-a week, "mini" four-week regime (standard programmes last ten weeks) and wondering if I have the bank funds to book a last-minute flight to flee the country.
The programme doesn't make promises to turn you into a sculpted goddess overnight. Instead it advocates "sustainable healthy lifestyle changes" and its impressive 85 per cent retention of girls seems promising. I text my old personal trainer in London for advice, who kindly forgoes his usual nickname for me of "Fatty boom-boom" (the "boom-boom" presumably being the thundering sound I make as I lumber around) and simply wishes me luck. My female friends squeal and say they'd like to try it too if they could find the motivation, while my infuriatingly naturally trim husband rolls his eyes and goes back to chomping on his burger and fries.
Leaving the flat on a still-dark and chilly Monday morning, I get to Sun Yat Sen Memorial Park in Sheung Wan and trudge towards the group of around 40 girls, who are yawning and nervously eyeing the instruments of torture our black-clad trainers are laying out in front of us. After some stretches we go through some tests of push-ups and planks  to record our individual base levels of fitness, which will be compared with our results at the end of the programme. I surprise myself by managing to double my usual plank time to a five-minute wobble, spurred on by encouragement from the trainers, but my previous avoidance of detested push-ups works against me and I cave in after a dozen or so. Tough but manageable circuit exercises follow in the 45-minute session, with girls split up into groups depending on their experience.
'I can do this! I feel great!' I think as the workout draws to a close. I smugly make my way to the office practically whistling, and when I sit down at my computer there's already notifications from the Facebook group from the trainers praising us on a good job and offering their advice over an online Q&A over the next hour, a feature that repeats over the next few days.
But the next day of intense circuits focusing on our legs leaves us all in agony, with day three no kinder as we are pushed to run, and run, and run, to keep blood flowing to our sore muscles. Day four is yoga, the next day another circuits session, and the following day a hugely enjoyable, if knackering, session of boxing. At the end of the sixth day I am exhausted and wonder how on earth I will repeat the process for three more weeks.
Bikini Fit's founder, Australian native and human wall of muscle Alex de Fina is a serious athlete who used to play state soccer and powerlifting at a national level, and is also trained in kickboxing and jujitsu. He brings his experience of training strength athletes and mixed martial arts fighters to Hong Kong's women who he says he wants to "re-educate" on the way they perceive health and fitness.
Watch: Sofia's Bikini Fit testimony
"Women are marketed so many fad diets and quick fixes on an emotional level, where they're told they can look like a celebrity if they follow certain steps," he tells me.
"We walk the hard road of educating our members rather than some agenda, and very much focus on the goal of sustained lifestyle change."
Although I don't realistically expect to have transformed already into a six-pack siren, still I'm a little disappointed at my weight remaining pretty stable at the end of the week. But I do feel energised and excited to see what the rest of the month brings, in both physical and emotional terms. Bring it on.