Trouble, the scientists say, reliably triggers a fight-or-flight response. It goes without saying that flight is not an option for those hapless holidaymakers grounded by Icelandic ash, and every well-brought-up reader is well aware that fighting solves nothing. But ignoring a biological urge to move by sitting still is the worst of all possible worlds; stress hormones surge and – denied their effect – they produce a disabling angst. So, what to do? The answer was hinted at by Gill Hornby, who – from the stranded shores of Tenerife – wrote on our front page yesterday that "only the aerobics is keeping us going". Regimented counting and blaring disco may not be an obvious way to unwind, but it raises the heartbeat and then produces a wave of calm when it slows back down. Boxercise is surely a decent substitute for the "fight" side of the equation, even if the modest heights reached on aerobic steps are at best a very poor man's soaring flight. Noisy and sweaty as it may be, donning Lycra to dance is a rare means of boosting flexibility, strength and cardiac fitness all at once. New research suggests that some of the benefits pass on to the next generation too: prenatal aerobics leads to lighter babies, and that in turn just might reduce the risk of the children growing fat later on. For those who will not be levered off the sofa by any amount of evidence about how much good it will do, Mr Motivator provides an armchair aerobic workout. Whether you are stuck on holiday or detained at home, the time is right to dance.