If you procrastinate doing something, it means that you plan on doing it, but keep delaying it for no real good reason. You keep making stupid excuses to yourself.
If you have an exam tomorrow but you keep watching TV instead of starting to study, you are procrastinating.
If you are planning to go to the gym for a good workout but for some reason can’t get your ass off the couch and are instead just thinking about going to the gym, you are “procrastinating going to the gym“.
You can procrastinate on bigger things too like starting a business. Who knows, maybe you are procrastinating studying English and that’s why your level still sucks compared to a native speaker! (Just kidding about that, but honestly, your life will improve A LOT if you stop procrastinating and start doing what you know you should be doing) It’s the same for everybody!