We recommend you take a look at the Les Mills Grit Series. These high-intensity sessions are short (30 minutes) but work you hard.

At these classes, you should leave your self-consciousness at the door, as the sessions take place in a room with a dozen or more people all sweating and pushing through their pain barriers in short bursts to explosive music.

Expect the occasional scream of pain … or relief.

Strength work and plyometrics combine in this high-intensity interval training, which the experts say accelerates your body’s fat-burning powers.

Instructors reckon you’ll shed pounds if you do their sessions on a regular basis.

The first class is free (download a pass from the Fitness First website), then it’s £15 per session for non-members. Classes will run until December – perfect for slimming down before a Christmas binge, we think.

What are you waiting for? Get cracking … then more importantly get cracking on those mince pies.

Classes take place at Fitness First gyms all over London


Image: Getty