I almost did the entire ceiling in that room today. I ended up with two five gallon buckets of ceiling texture that I scraped off. I have a little touch up but the progress was apparent.
I also ended up with ferociously cramping upper arms and shoulders. I worked today until I couldn't hold my hands above my head any longer, came home and ate, took a shower, and fell asleep for about an hour. I awoke to the most excruciating cramping I have ever experienced in my upper body. It was like those middle of the night cramps in your calves when you are low on potassium but on both sides... I got up to get under the hot shower again and was in so much pain that all I could do was spin disoriented in the middle of the floor as tears started to squeeze out of my eyes.
I'm used to typing at waist level for hours on end as my most strenuous activity. I'm not used to five consecutive hours of scraping off ceiling texture above my head. I'm out of shape obviously... so if I live through this lame shoulder bullshit, which I likely will but not without being whiny and griping about it until it's over, I just might accidentally better my physical condition (not to mention make the house visually appealing).
On a twisted side note, I kept getting the grainy chalk like shit in my mouth. Eventually I realized that it was because I was doing it all with an open mouth grin. I was as happy as a pig in shit.