The Daily Mail loves its scare story, "lettuce gives you cancer", but one time there is something with a clear cut connection between action (driving everywhere) and outcome (10 years off your life), the DM refuses to acknowledge this, instead going for "Nanny State to increase parking costs".
If the DM news crew though it through -and believed the NHS reports- then they'd realise that shortening the lives of daily mail readers is bad for their long term income plans, unless they plan to "hook" another generation of daily mail readers. The demographics of printed press sales mean that isn't going to happen -unless they can convert this to page hits of people that don't use flashblock and adblock in their browsers, then even their web site's business plan is weak.
It should be in the DM's interest to get its readers to do some exercise, unless there's another goal. What? Well, there's the advertising revenue to think of; all the Car adverts. That hasn't stopped the Times.
It's most likely that the DM needs their agenda "europe to ban cheddar cheese", "asylum seekers groom teenage girls for sex", to sell papers. If there weren't scare stories on the headline, (or royalty joy stories), then people would leave the DM copies on the stalls as the newsagent, and so their paper sales -the ones they depend on the most- would fall.
That's something to consider as a tactic -if they could be switched into treating travesties of justice by law-breaking lorry drivers as something to put on the front page, then maybe they'd start to get through to an audience which, like it or not, represent a large proportion of suburban England (no comment on Wales, Scotland, NI), But the DM isn't going to do that unless they think their audience would care -and if they don't, they won't. Maybe the tactic is that their children, and their grandchildren cycle.