Turning up to a Gymbox class called Cannabliss (membership from £73, gymbox.com) is my twofold nightmare. First, group exercise has always struck me as torture plus humiliation. Second, drug talk makes me feel 107 years old. When I hear anyone rhapsodising about hydroponics or closed-loop extraction or how to core an apple bong, I have a tremendous urge to shout: “Why didn’t you stay in school, you’re obviously smart?” Even if they’re in their early 40s. I suppose if we rebranded Stem subjects as Seed and Buds, we could stop failing our weed heads. Anyway, the idea of enduring their company while on a crosstrainer makes me want to pull a … whitey, is it? In my long shorts, I may as well have turned up to class wearing a baseball cap that reads: “How do you do, fellow kids.” I also arrive late, to fit in better with the apathetic stoners. It is my first mistake. They are all there, in their Lululemon and Nike athleisure gear, fit young professionals who regularly go to the gym and let...