I struggle a lot with my motivation. It's not always so much that i don't want to do things, but that i find myself physically incapable. everyone used to call me lazy when that would happen because, unlike you, i'm the only one with ADHD in my family. What i've found that helps is small physical stims. Find one thing that you can do like with your hands or with your foot that's small but manages to give your mind something other than your lack of productivity to focus on. And while part of your mind hyper fixates on that, you'll be able to get up and start doing things a little easier. At least that's what has helped for me. I typically just rub the sides of my fingers together and focus on the feeling of the friction.