I'll be 56 in 3 months.
I've been about 60-70% "primal" my whole life without realizing what it was called until the past few years. I was raised on meat and veg with occasional potatoes (usually with Sunday dinner), and only had bread as a school kid for my school lunch. Over the last four years or so I've gradually become more primal, and now am about 90-95%. I found the Primal Blueprint two years ago and was happy to see that there's a name for my craziness!
I've never had a weight problem. My blood pressure, cholesterol and blood sugar have always been ideal. I look around 10-15 years younger than I am. The only medication I've ever needed is thyroid hormone because I've had thyroid surgery. My fitness level is better than 98% of the general population.
Perhaps primal isn't sustainable for the Earth, but for me it's completely sustainable. I don't think it's sustainable for my doctor's income, either, as I only go in for yearly check-ups!
You make your choices, and you live with them. In the end, you are those choices.
"Strength is the mental and physical fortitude to endure, resilience to bounce back, and force to create change, allowing you to thrive in any circumstance and through any adversity." TrPAssassin