Cities fit for people, rather than exhaust pipes; cities where residents are happier, have improved physical and mental wellbeing, sleep better, live longer. In our age of deficit fetishism, the success of a policy is judged by its economic returns, rather than whether it improves the lives of living, breathing human beings. But a new study suggests that cities that invest in encouraging their citizens to be physically active reap both financial and human rewards.

For every pound cities across the world invest in walking and cycling projects, for example, the returns average £13; here in Britain, it could be as high as £19. Investing in green spaces and public transport clears both the air and the roads, and makes cities pleasant places to live.

Prosperous nations have the wealth to invest in their cities, however much today’s politicians protest otherwise

Here’s a study that tells a story that has been badly told in the age of austerity. Apologists for balancing books by slicing through public expenditure had an easy story to tell, and they did it well: there is a gap between what we spend and what we earn, and that gap must be closed by reining in spending. The idea of investment – that spending money now will more than pay for itself in the longer run – has been done a disservice. But the University of California’s academics sum up the false economy: cutting back on making our cities decent, enjoyable places to live ends up costing us far more.

Take cycling. A confession: after taking it up five years ago, I became an insufferable cycling evangelist. London was a rabbit warren of underground stations when I first defected here from the north; cycling is the perfect way to acquaint yourself with where you live.

Cycling claws back time to think and contemplate that the age of smartphones and social media stole away; it burns calories without stressing your joints, tackles stress levels and makes you fitter; and it means you are one less car on the road or one less passenger crammed against the window of a bus or a train. Back in March, Nick Clegg announced millions of pounds to support the cycle city ambition programme, to make cities more bike-friendly, rightly pointing out that the research shows it “could save billions of pounds otherwise spent on the NHS, reduce pollution and congestion, and create a happier and safer population”.

Alas, the investment is an early casualty of a Tory majority government, with George Osborne hacking away £23m. A short-term saving: but at what long-term cost? The same goes for our precious green spaces, where we can walk, jog and run in pleasant surroundings. Past investment paid off, but parks are not a statutory service that councils are obliged to protect, making them early casualties of cuts. Last year, 86% of parks departments said their budgets had been cut, with nearly a third experiencing drops of at least a fifth, and two suffering cutbacks of 50%.

The Campaign for Rural England suggests that funding is “in crisis” and “discretionary spending” will drop by around 60% by the end of the decade. There will be no one employed to look after the parks, it fears.

Given that eight out of 10 of Britons live in an urban area – more cramped together than in virtually any other European country – it is sheer vandalism to allow our parks to go to rot. It will mean a less happy and less healthy population – and again, that will end up hitting the nation in the pocket.

We’re cutting back on sports and leisure budgets, too: £42m hacked away from council budgets in the past five years was rightly condemned for “storing up problems for the longer term” by the Sport and Recreation Alliance.

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As things stand, eight out of 10 of us are failing to meet the government’s target of at least 12 sessions of “moderate exercise” over the course of a month. As facilities are cut back and green space deteriorates, that already poor record will surely only worsen. It means we end up spending money on preventable diseases and on mental distress.

It’s bad for the economy in other ways, too: as the Californian academics point out, those who regularly exercise are less likely to take time off work. As for our public transport: we have a dazzlingly inefficient, fragmented rail system that devours public subsidies and makes train travel in Britain among the most expensive in Europe.

London benefits from twice as much spending per person on transport as the rest of the country, with unacceptably poor services elsewhere. Londoners have a regulated bus industry; elsewhere, buses are often infrequent, pushing people into their cars, with all the pollution and congestion that brings.

Yes, it costs money upfront to create cities with well-kept parks where we can walk with our families or jog with our friends; to support those dispensing with cars in favour of bikes; to encourage burning off calories in easy, fun, fulfilling ways. But it costs so much more in the long term – not just financially, but also in our mental and physical health. Prosperous nations have the wealth to invest in their cities, however much today’s politicians protest otherwise. If they fail to do so, our lives will be gloomier, our waists will expand, and our health budgets will take up the slack. A shame indeed.