In your opinion, what should I do for running, I can barely run more than 400m [0.25 mi] in one go, which means that I can't even do a successful baseline test
It will only be unsuccessful if you don’t finish. You can walk as much as you’d like, or run as much as you’d like—that’s perfectly fine! I promise you’re not the only person who feels this way.
A baseline is important because it helps you identify your starting point. Once you’ve set that starting line, you can define a finish line. After you cross it, you establish a new finish line, making the previous one your new starting point. It all depends on time.
