"I know what to do, so why don't I do it?"
The primary reason is because you set yourself up with your beliefs and thoughts.
The brain craves the familiar. We like to stay on familiar grounds. Once the brain determines the familiar patterns are going to
be, then all of our other responses will going to be consistent with those patterns.
When we risk change, we also risk failure.
What holds us back and what prevents us from achieving our dreams, from realizing our success... is nothing more than the emotions of
fear (specifically the fear of failure).
If you are willing to devote the necessary time and effort. And if you badly want it enough, you can
get it. The reason why so many people do not realize their dreams are simply because they don't believe they can
and they fear the failure which could happen when they institute any sort of change in their life.