What is it? Project Fit is a class that combines intense cardio intervals with punishing bodyweight exercises. It’s also the first thing I’ve done for this column that genuinely made me throw up inside my mouth.

How much does it cost? Twelve quid for a 35-minute class, £20 for an hour.

What does it promise? A blisteringly intense HIIT workout that burns up to 1,000 calories per session. The onus is on you to work as hard as you can throughout. As Project Fit is fond of telling you, it’s you v your body.

What’s it actually like? I decided to give my body a head start by foolishly wolfing down a retrospectively way-too-big cake on the train to the class. This wasn’t much of a problem during the first treadmill session, where your speed increases every 30 seconds until you’re hammering along at full pelt. Nor was it an issue during the first bodyweight session, full of lunges and squats and press-ups. But then came the second treadmill session: five minutes at maximum incline. This was horrible. This is where I struggled to break into a run. And, yes, this is where the cake made its unwelcome reappearance. After that, the rest of the class (two more floor sessions, one with TRX straps and a final run) lurched by in a blur. Hands down, Project Fit is the hardest thing I’ve done for ages.

Best and worst bit If I did Project Fit regularly enough, I’d soon be in the shape of my life. The worst bit? Sadly it’s available only in London. Also IT MADE ME VOMIT INSIDE MY MOUTH. I thought I’d made that clear. Have you ever tried running uphill and swallowing vomit at the same time?

Is it worth it? If you lay off the cakes.