I have tried and failed to remember/identify this short story or short film (can't remember which!) of a guy who goes about his normal life with a nagging feeling that something is controlling his arm or his arm is stuck on something that he can't really feel. He barely perceives that something is "not quite right".
Eventually he's able to move his phantom limb, press a button, and trigger a "Wake up" command. He discovers that he's in a space ship life support pod on a vessel that is about to explode or run out of air and he has mere minutes to live. The pod was giving him a time-lapsed alternate reality. In the end he elects to press the button again to go back into the matrix where his last few minutes of life will stretch out for decades in the virtual reality. Wish I could remember the title, would love to read or watch it again.