This is what I need! Perhaps we all do.

A Personal Trainer.

Come on you fellow commuters, hop to it: first of all we will jog up and down the carriage, then do star jumps in the aisle (5 sets of 15), weight lifting our briefcases and rucksacks up to the luggage rack and down again 10 times, and then hold the plank position until the next station.

After that the new guys can do a session whilst you take a breather – a kind of relay. Up for it?