As I finish my first session with British Military Fitness – having spent 50 minutes exercising in the lush parkland of Hampstead Heath – I can’t help but give a metaphorical “stuff you” to mates who said it would be the death of me.

“Gimme 20 push-ups you lazy so-and-so,” is what friends joked I’d experience.

But the reality is far, far from this.

The sessions, held year-round on weekends and evenings in parks all over London, are designed to provide a strenuous workout, but instructors have a good blend of encouraging you on without resorting to harsh or belittling words.

The sessions mix running and strength exercises for a great all-round workout, and are divided up for different fitness levels, including less-fit beginners.

DANIEL LANDON

» Classes all over London (020 7751 9742; britmilfit.com). From £35 per month.

Verdict: Shaping up