I also have difficulty running with a twisted ankle
Playing like a chimp: Never play chess with a migraine headache

My most embarrasing loss ever? I quit when I realized my opponent had the white pieces!
I've had people abort when I had the white pieces. I suspected it was someone who wanted to play white. I think they were breaking bad.

I think we've already established that.

There's nothing I've loved so much in life as winning a game of USCF/FIDE tournament chess, studying chess, and playing, in general. I had severe migraines in 2010 when I was diagnosed with diabetes, probably from a combination of staring (at a board for even a minute or two) and extreme fluctuations in fluid volumes in brain capillaries. I was forced to give up chess until I was physically fit enough to avoid swings in blood sugar, etc. I played with a migraine in just one USCF game (against a rival), and lost quickly and shamefully. I wasn't the same player.
My USCF flatline, for effect :

An acquaintance of mine who was rated in the 18xx range just drew a game against a GM in the US Open because that GM had a migraine.
I stopped playing chess competitively for several years in part due to migraines.

I pretty much quit OTB chess after losing a game for the city championship while fighting a headache for hours. Chess is no fun with a headache.
I've never had a migraine problem but if I play too many rapid games in a row I'll start getting a headache. It definitely changes the way I play. I wouldn't play a game with a full blown migraine, forget that.

Even one glass of beer does this to me.
Interesting. My chess club meets in a Mexican resturant where most guys drink beer while playing, I thinks it's a ruse to get out of the house.

Physical body can never be seperated from mental one.
You'll have to wait and see at the point of your ownmost possibility, which is not to be outstripped.
It's not just migraines though. Sometimes it is possible to play like an idiot just because I'm a bit tired, or in a bad mood. The odd thing is, sometimes I just keep playing anyway, getting more and more irritated with each useless performance. I guess it's a bit like being addicted to gambling. At least you only lose 200 points, not £200.
I don't know why I try to play chess when I have a migraine headache. I once dropped my tactics rating 200 points in doing so. Here is what has to be my most embarrassing loss ever. The brain just doesn't work too well when you have a migraine. I think turning a Sicilian into a King's Gambit was just too much for my migraine-addled brain.
Just for fun, post your most embarrassing losses.