In the health section of The Spectator, I suggest taking up pugilism:
Though I never competed as a boxer, I was a sparring partner for several who did fight on an amateur circuit. Sparring – actually fighting another human being – is the most intensely physical thing you’ll ever experience. […] It is also exhausting in a way that treadmills and weights could never be. The average self-important runner, who thinks he or she is just so fit – yes, I’m talking to you – will gasp and wheeze through the first three-minute round.