Most people who try to change their running technique go through a frustrating period where the new technique does not feel natural, and they need expend a lot of mental energy focusing on maintaining good form. I certainly went through this. In fact, I still regularly spend time monitoring the speed of my pull. However, I spend much less time thinking about my technique than I used to, and things I had to think about before, are completely natural for me now.
While Dr. Romanov was visiting, we visited the Dr. Lieberman's lab at Harvard. Dr. Lieberman asked Dr. Romanov to run on his treadmill in order to collect some data on Dr. Romanov's technique. First, Dr. Romanov ran naturally and naturally for Dr. Romanov means he ran with excellent technique. However, when Dr. Lieberman asked Dr. Romanov to run with a heel landing, things got a bit humorous. Dr. Romanov has been practicing good technique for so long now that he found it very difficult to land on his heal. Dr. Lieberman actually had to try to "teach" Dr. Romanov how to run with bad technique. The moral of the story is that it is difficult for most people to change their running technique. However after a while it will become second nature.
Below is a picture of Dr. Lieberman instructing Dr. Romanov on how to run with bad technique. For Dr. Romanov, bad technique is as unnatural as good technique is for most other runners.