You can do the thing that you can't do in your mind

I think quite the opposite.You can think and imagine what you can't really do.For example,I have numerous dreams in which I am literally flying,teleport,do more than two things at a time,think andspeak different things. I think you can do this in your mind,but I don't suggest trying to enact what you think,because not all you think is the best.

I think its called "taking risk". Taking risk to something you think you cannot done. Taking risk to something do don't expect others to you. Taking risk to something your afraid off. And once you accomplished something by doing it and take the risk, you would end up feeling happy and proud of what you had accomplished. Many people already reached their success simply because they take the risk and they had succeeded. Its for us to also take that risk for us to become one of them.