It is sometimes very difficult - I gave up trying to convince anyone and just started doing what I could (and what was most important to me) and ignoring the rest. It's not easy when they are harping on you to do more, or calling you lazy, wish I had a solution for that.
The only thing I know of that has helped anyone convince those who don't accept our limitations is "The Spoon Theory"
/cdn.totalcomputersusa.com/butyoudontlooksick.com/uploads/2010/02/BYDLS-TheSpoonTheory.pdfMaybe some of our other members have some thoughts?