I am the worst runner in the world

I literally had someone casually walking keep up with me. The other day I had a kid a hundred yards ahead of me and they stayed ahead while I was moving the entire tine. A mile and a half and Im dead. I really hate this muscle weakness crap and can’t wait until I get treated. I literally used to run this same exact route with fifty pounds of weights on me without stopping. Now I got 3/4ths the way into it and had to walk the rest.