Murphy's Law of Getting Comfortable
"You can struggle for hours to get bearably comfortable --- i.e., warm enough, free of aches, etc. --- but then just as soon as you actually DO succeed in getting comfortably 'settled in' at long last, something unavoidable will come up dat will force you to relinquish said comfy position to go and tackle some disagreeable physical activity which will cause you to get chilly again, experience more bodily pain, etc."
Two "sister" examples of Murphy's Law of Getting Comfortable would be "Murphy's Law of Falling Asleep" (i.e., you can struggle for half the night or more to fall asleep, but then immediately after you finally drift off, someone or something comes along to wake you up again) and "Murphy's Law of Personal Comfort" (i.e., however comfortable you become will be in direct inverse proportion to da comfort of others in your vicinity; for example, da nearer you sit to a heater/air-conditioning duct, da more you will block da flow of said "moderated" air, and so while YOU YOURSELF may indeed feel more-tolerably warmer/cooler, EVERYONE ELSE in da room will feel even more uncomfortable than you would have if you'd sat a more-reasonable distance from said climate-control orifice. Or if you recline your seat on a public-transportation vehicle, said tilted-backwards back-rest will encroach on da extremely-limited "personal space" in front of da passenger seated behind you).