I'm really conscious of the importance of exercise, especially as I get older — I've read enough of the research on this to know how big the health implications are, and I've even heard Muir Gray talk twice. But I find it really hard to exercise just for the sake of exercise: I can't see myself ever joining a gym, buying household exercise equipment, or anything like that.
Under normal circumstances I average about 8km cycling a day and maybe 3.5km walking, which is probably just enough to maintain aerobic basic fitness. (Though I'm missing any kind of upper-body muscle workout.) But half my cycling comes from my commute and almost all the rest from other regular trips, getting myself or Helen to gamelan or choir. And a good chunk of my walking comes from the school run, even though that's only 1km return, with most of the rest coming from walking to lunch and morning or afternoon tea, or occasionally to dinner.
So most of my exercise has just disappeared now we're in lockdown. I try to get myself out of the house for a fast 45min walk each day, but that can be a struggle — I've averaged 2.5km/day over the last month — and it's even harder getting Helen or Camilla out. I try to find a new location or route for each trip (the Southfield golf course is nice with no golf happening), but am thinking I need a long-term goal like trying to walk along every street within 2km of our house.
I had the thought that rationing of exercise outings might make them more attractive, but that doesn't seem to be the case. There are more people out and about in East Oxford in the middle of the day, but there's no school-run bustle, no crowds in town shopping or going to work, no crowds on Cowley Rd, and so forth, so I think my experience is typical and overall physical activity is actually down. Presumably the third of English adults who didn't do even ten minutes of brisk walking a month before still don't.
Which is why interventions such as Low Traffic Neighbourhoods (PDF intro) are so powerful. Make driving local trips a little less easy and convenient, and walking or cycling safer and more comfortable, and some people will shift to active travel for trips they do regularly. (One study suggested an average of 41 minutes extra walking or cycling per week for residents in the Waltham Forest low traffic neighbourhoods.) Since these interventions affect whole neighbourhoods and are permanent and on-going, they are in the long-term vastly more cost-effective — despite their headline costs — than encouraging exercise, subsidising weight-loss programs, and so forth.