Desidiousness. Lat. sitting too much; slothfulness, idleness, carelessness. – A New Dictionary of the English Language by Charles Richardson, 1836

I believe most distempers proceed from too much sitting still. РMarie de Rabutin-Chantal, letter to her daughter Fran̤oise-Marguerite de S̩vig

I shall be compelled to buy a standing-desk, which will cost me from two to three dollars, as the older students advise me to have one as necessary to my health. – James Stokes Dickerson, letter to brother, 1842 October 13th

Workers at home who have aching backs and but one writing desk, and that a low one, will find great relief from writing in a standing position (if a recess is out the question), if only for fifteen minutes. My standing desk is a broad mantel shelf. – B.G.A., “Helpful Hints and Suggestions,” in The Writer, August 1887