Why is a thorough assessment protocol so important when it comes to developing a personalized fitness routine? 

This is the easiest question. If you don’t know what a client is capable of doing safely, where a client has pain, where a client’s movement is restricted, and where a client’s strength is deficient, It is impossible to know what movements will help or hurt them. You need to establish what needs to be mobilized, what needs to be stabilized, and how those restrict the client’s pending goals. If you're not assessing, you’re guessing. The real question is, how can you develop a personalized routine without assessing?

Ryan Golec