This article is written by the company that it touts. It is an advertorial. It offers no data on the number of RNs who have entered this field, with no specific examples or anecdotes. Therefore as a reader I have no choice but to be circumspect about its claims. Of course an RN can take a physical trainer class and then be a physical trainer. They don't need an RN license to be a health coach. It's a career change, just like going to law school would be a career change. They wouldn't be using the RN license in their job as a health coach without getting into trouble.  It would just add to their background. However I do think that without RN work some RNs would make great trainers if they wanted to enter that field. They would have to be very careful about dispensing medical advice, however.