People will often ask me: "Do you have to be fit in order to dive?" And I will often ignore them until they go away.
But occasionally I will reply: "Yes, you need the lungs of a sherpa and the physique of a Saskatchewan lumberjack."
This is my new strategy for keeping numbers down. I call it "lying" and, while it may be ethically questionable, at least it's less drastic than my old strategy of the annual cull.
Still, there is a case for divers maintaining some degree of physical fitness. As I've learned to my cost, it takes a fair amount of brawn to rip a porthole off a designated war grave.
In fact, it was the subject of diving fitness that first prompted me to write to Diver, almost 70 years ago.
The magazine carried an article on yoga - urging fat, beer-swilling hooligans everywhere to bin their Capstan Full Strength, trade in their porky scratchings for a pint of slippery elm food and follow the True Path of the holy men of ancient India.
My response to this suggestion was to produce a sober, academic analysis of the psychology of the typical diver. I called it Smash The Yoga Nancy Boys.
Nevertheless, I have always been a tireless champion of keeping in shape. Having run across the Sahara and completed a marathon on the slopes of Kajenjunga, I now humbly present my own, patent pre-season fitness regime for divers, soon to be released on DVD (Time-Warner, £13.99).
Day 1: Retrieve your wetsuit from the loft. Remove any extraneous lichen and cockroaches. Attempt to unfasten the zipper (this can be found beneath the thick brown-and-white crust of oxidised metal to the left of the centre of the jacket). Wearing a light cotton glove will help to reduce bleeding sores on the thumb and forefinger.
Warning: on no account attempt this exercise in the presence of children or those of a delicate disposition.
Day 2: Put on the wetsuit. As it is at least two sizes too small, you'll exercise the main muscle groups of the arms and shoulders. But the main benefit will be to the abdomen, which you'll be forced to haul in tighter than a whore's corset. Don't be alarmed if you experience a slight discharge of stale lager from the nose and ears.
Day 3: Having slept in the wetsuit, enjoy a gentle morning jog of not more than 6 or 7 miles. Slow down at the first signs of heat-stroke - you should expect some minor giddiness and disorientation, but the onset of projectile vomiting can provide a useful benchmark.
After a couple of weeks, you may wish to wear a weightbelt, adding lead over time as your overall fitness improves. Remove the wetsuit in the evening. You should allow about two hours for this exercise.
At first, you may find it beneficial to retain the services of a brace of male psychiatric nurses.
Day 4: Sleep.
Day 5: Pushing a fully-laden club van sounds tougher than it really is. Once you overcome the inertia and the limiting friction, it is possible to keep up quite a lively pace. So, after a month or so, try the exercise on a slight-to-moderate incline. Or better still, uphill after heavy rain in the parking field at Lulworth.
Day 6: Tucking a 70hp Yamaha boat engine under each arm, run up the pebble beach at Chesil. When you reach the summit, orally inflate a 5m work boat. Repeat until tired. Bear in mind that the NHS waiting list for hernia corrections is approximately two years.
Day 7: Sell diving gear at car boot sale. Take up whist.
For more in a similar vein the book Blackford's Diving Life and Times can be ordered from Underwater World Publications, price £7.50 (tel. 0181 943 4288).