It is our general belief that the Dark Hadou and all of that is complete bull. That is not entirely accurate. While it does not manifest in a visual way, you can feel when someone is behind you, right? That's KI. Ki is real and there have been videos documenting its existence. Now, you will not be able to shoot a beam of ki out of your hands, but you can control it through years of training. I have only begun to scratch the surface on how to use it. You are on your own with that one.
The one thing we can really say about Street Fighter is Ryu's extreme dedication to the martial arts. He is always training and working as hard as he possibly can to make himself unstoppable. He constantly fights and sparrs with Ken and the others. In every movie you can see him train. If you put forth that kind of dedication, you can be great as well!