That just isn't practical is it. Some people have tiny flats and no gardens. Do you expect them to run around in a tight circle 150 times? I'm a bit gutted that all my usual avenues of exercise are curtailed, but I'm grateful I can still go for a run - not massively enjoyable but a small saving grace in the absence of anything else. If I couldn't even do that I'd go mad.
PS Have a look at the guy who ran a marathon on his balcony.