Ultimately as much as we love individual responsibility, the truth is only the lucky few have the ability to freely choose their lifestyle. For the rest of us we have to conform to the unhealthy lifestyle that society demands of us.

To live a life that's even remotely healthy we have to dedicate a significant amount of the precious spare time we have just to undo some of that damage.

I do not believe we are predisposed to adopt sedentary lifestyles. As kids most of us are very active, but we are taught to be sedentary. Both academically and professionally we are most rewarded for sedentary activities: doing extra coursework, building your resume. Is it any surprise we develop a sedentary lifestyle when such a lifestyle is most rewarded?

I think rural life is too romanticized though. It will avoid the diseases endemic to sedentary life, but there will be different health issues instead. Preindustrial agriculture and generally jobs with lots of physical labor are not easy on the body. Coronary heart disease and maybe diabetes and dementia will be replaced by work-related injuries and arthritis. There is a reason many countries allow such people to retire earlier.