Yes it does barb...
Could you do just one shelf each day? So not all that leaning and bending all at once?
We have three showers , and are cleaning the tiles , one shower each day..
At times, i learned a trick , on jobs i hate doing..the trick is to set a timer..and commit to only ten or 15 minutes at a time on tough jobs, or ones you just do not want to do..
Sometimes i only commit to one corner of a room at a time, breaking jobs into more manageable portions...ha ha some of my corners are pretty daunting..