Higher-income Americans are already the group that exercises the most. According to the American Time Use Survey from 2015, the poorest quartile of the population gets about half the exercise of the wealthiest quartile:
I know plenty of people who pay absurd amounts of money to be members of gyms like SoulCycle. I grew up as a runner; I'm currently a cyclist. I've always shunned fitness trends, especially those that require you to go to a special class, buy special equipment, or pay a lot of money. Why not just go out for a run? Or lots of people own bikes already, just go for a ride, right?
What I didn't realize is that I was lucky to have grown up in a fairly rural area of Massachusetts. Nothing about my environment made it difficult for me to exercise outside on my own. All I had to do was get to the end of my driveway and there were miles upon miles of safe road for me to run or ride on.
Then I moved to Austin, TX. The neighborhood I live in has multiple luxury gyms within an easy couple minutes walk. But the roads are not good for running or cycling. It takes me about five stressful miles of riding before I'm on road where I feel safe on my bike. And I'm sure there are areas of the city that are worse deserts of exercise-safe space.
These luxury gyms are great, and super effective . . . if you can afford them. If not, you may be stuck in an area that discourages you from exercising.