How did this happen, you ask me. Let me explain.
I did an exercise video.
The story is as follows. I am a reasonably fit person when it comes to stamina. When not laid low with plague I could happily get up tomorrow** and walk 20 miles without a twinge, assuming I had decent shoes on and it wasn't all a 1 in 3 uphill. But after a couple of years of not being terribly well, my cardio-vascular fitness isn't what it might be, and my generally rubbish upper body strength is even more rubbish than usual.
I decided that this needed to be remedied. However, it is the middle of winter. The weather is foul. There's no way I have the motivation to go running regularly. I am too mean to fork out for the gym more than once ever few months. Aha! I thought, buy an exercise video. 20 minute bursts, I might actually be bothered to do that. I can even do it in bare feet, thus promoting balance.
So I did. And it turns out that my muscles do seem to have got a fairly good work out, if the pain is anything to go by. It wasn't a problem at the time. It's just that I woke up this morning and I can't move any more.
On the plus side, I understand that the agony really is proof that it's worked, because the muscle damage that it is symptomatic of is allegedly building better muscle. If that's the case, I feel I ought to look like Miss Universe.
It is not too bad. I haven't actually strained anything, it's just a fit of physical pique, and it will pass soon. But please could it do so by tomorrow morning.
*I always assumed you just have a couple of biggish muscles in the thighs, but it turns out there are lots of small ones instead. See, pain is educational.
**Not actually tomorrow. I could have on Saturday.