Quite often when someone I meet finds out I’m a runner they say something like “I couldn’t run a mile.” For most people they’re really saying “I don’t want to run.” There are very few people that could not train for a few weeks and run a mile. Most people just don’t have that desire, and I get that. I say the same thing about playing the piano. I would love to be able to play the piano (yes, Mom, I should have stuck with the lessons 40 years ago). But I don’t want it bad enough to take the time to learn.
So, if you want to be able to run, just start. Don’t wait. Put your shoes on and start walking. Then in a week or so mix some short jogs with your walking, then keep increasing the time. There are many websites that have programs for beginning runners. Find one and start. Or don’t say you “can’t run”, just say you don’t want to run.