Terence Blacker: A guide to the 11¾ things to do before you're 50 (and I should know)

Some advice for the outdoor types at the National Trust

Has someone been putting Benzedrine in the tea at the National Trust's headquarters? Hardly a week goes by without that once-staid organisation coming up with another headline-grabbing protest, survey or campaign. Responding to the growing urbanisation of childhood – more children know what a dalek looks like than they do a magpie, according to its research – the Trust has published 50 Things To Do Before You are 11¾, a list of jolly outdoor activities for children. There is an element of bias here. Playing outdoors is surely just as important for those of us who passed 11¾ some time ago. Here, turning the National Trust's formula on its head, are 11¾ things for you to do before you are 50, with some additional tips as to what to avoid.

1. Play a unisex team game outdoors. It can be cricket, football, even that favourite of Lord Prescott, croquet. The type of sport is less important than the presence of players of both sexes and across the age spectrum, who will reduce the danger of a silly, insecure male taking the thing too seriously. Avoid: on-pitch brawls, daddy tantrums and heart attacks.

2. Get your hair cut. In the hippest parts of London, hairdressing has become an open-air performance event. You can get your hair cut in the middle of Brick Lane market, watched by shoppers and photographed by tourists. You are outside, almost always improving your appearance, and the centre of attention. What more could you want? Avoid: asking for a cappuccino and a copy of Vogue. There is a limit.

3. Have an impromptu sing-a-long by a bonfire. It is an odd fact that the most woeful musicians can sound almost all right when in the open air, particularly when the crackle of burning branches helps drown them out. A drunken musical event to a bonfire setting will induce a contented hippy vibe on the happy, shining faces of those staring into the flames. Avoid: Mr Tambourine Man. It starts well but, by the time the singer gets to the jingle-jangle morning, everyone's bored.

4. Go on a protest march. It can be against the cuts, pornography, hunting, Donald Trump. What matters is that you are out there, braving the elements on behalf of a better world unlike those wimpish, whey-faced online protesters. Avoid: breaking glass, urinating in a policeman's helmet, being interviewed, looking mad, on News at Ten.

5. Camp. It is a controversial item to include because, for some, a combination of the British weather and proximity to strangers, their mewling children and noisy sex-life is a sort of hell. The point of camping lies in the pleasure you derive on your return from the everyday comforts of life: a bath, an oven, a TV, a mattress. Avoid: the Daily Express reader in the next tent who wants to discuss immigration.

6. Make something. The task need not be much: bricks under the rabbit hutch, a plank nailed over a hole in the wall of a shed. It is the doing of it which will put you in touch with the frontier spirit of your forebears. Avoid: talking about DIY to anyone.

7. Destroy something. In its way, that can be even more satisfying. Avoid: cutting off a limb.

8. Enjoy a smoke in the open-air. So what if you are a non-smoker? You know, in your secret heart, that there are few smells sweeter than that of tobacco smoke rising slowly in the balmy summer air. It is worth remaining friends with someone who smokes simply to be able now and then to enjoy their habit, passively and free of charge. Avoid: discussing smoking.

9. Have sex. There is a school of thought, anti-pastoral, unromantic, which argues that acts of intimacy, however fleeting, are less pleasurable in the open-air. The cold is cited, and the damp, and the danger of being watched by the local Pervy John. For most people, though, these hazards add piquancy to the experience. Briefly – very briefly sometimes –they are at one with the creatures of the wild. Avoid: sand.

10. Go for a walk in ghastly weather. No country does nigglingly unpleasant weather like Britain: from the wind on the Norfolk beaches to the unannounced downpour that is the speciality of Cornwall. Embrace it. Take a bashful pride in its cussed awfulness. Avoid: Ramblers Association walks.

11. Visit the Antiques Roadshow. It seems only yesterday that you were going to the Radio One Roadshow; now you can watch Fiona Bruce and her experts without even feeling embarrassed. You have grown up. Why not join the crowd in person when they visit a grand house near you? Avoid: being seen by your friends gawping in background as Bunny Campione appraises a cake-stand.

11¾. Go to a festival. Attend the smaller, fringe events in the sun. Avoid: the mainline event in the evening, almost always a let-down. Head home before the rush, feeling mildly smug.