[Simons] You're going to tell us what it is, aren't you...? Sorry to hear of your case, it must be horrible to face up to confinement. Very glad you have found a solution.

[Simons] Yeah, what is your fix for the problem? (I bought a treadmill on Friday. Half of it was delivered on Saturday, the other half came this morning. I have paid for it by not having to buy petrol to drive to work for the next 6 weeks. I am imagining walking and listening to half-hour episodes of the Goon Show or Poirot or Paul Temple)

Well it's a home hack; I realized my futon base is at a usable height for 'step training'. Really it's far too high for proper step training but as I need the equivalent of running up at least 6 flights of stairs two steps at a time it'll do.
Normally a divan-like bed would be too soft, but mine's got two tatami mats in it so it's firm enough to step on repeatedly.
For restless legs, the NHS suggestions include taking a hot bath in the evening, or applying a hot or cold compress to your leg muscles - only cold works for me. In fact I also discovered that my legs don't get twitchy as long as they remain cold, so I sleep with not just my feet but my legs outside the covers, and provided it's not too warm a night that also works. Unfortunately my exercise tolerance and cold tolerance are increasing with practice, so my legs and I are locked in an arms race.
And when it's too hot, tiring them out (by any expedient method) is my only fix.

[Simons] Tried lying on your back and pedalling furiously?

I haven't actually, but that probably wouldn't provide heavy enough resistance to work against.

Strap bricks on your feet?

[Pablo] No, that's cruel. Poor bricks.