Not the OP, but as I live in a "lifestyle city" (Knoxville, TN) there are several middling big cities that are in close proximity to activities (hiking, climbing, skiing, beaches, etc).
Pretty sure the cities the OP was referring to are Boulder Colorado, Boise Idaho, and Chattanooga Tennessee. My family prefers Knoxville due to it being closer to the Smoky Mountains, but Chatannooga was on our list when we were deciding where to live.
Thanks for explaining it!
I didn't have also a clear grasp of the term "lifestyle" and "lifestyle city".
The term life-style does not have a clear semantic meaning understandable from just the word 'life' and 'style' but it seems like it has a very specific meaning attributed culturally by people in the US (or maybe generically English native speakers).
Pretty sure the cities the OP was referring to are Boulder Colorado, Boise Idaho, and Chattanooga Tennessee. My family prefers Knoxville due to it being closer to the Smoky Mountains, but Chatannooga was on our list when we were deciding where to live.