How would you define middle-age, old-age, and elderly without using age as a standard? 

How would you define middle-age, old-age, and elderly without using age as a standard?

Using 200-300 words APA format with at least two references. Sources must be published within the last 5 years. There should be a mix between research and your reflections. Add critical thinking in the posts along with research. Apply the material in a substantial way.