Extinct instinct

I wrote earlier about my four-legged personal trainer. She's still trying to do her job and get me out walking, but the colder weather has made me more stubborn. Forseeing that this was coming, I joined the local Y about a month ago. My thinking was that I could do weight training there as well as walking on the track in cold weather. I am still doing Zumba once a week and I still walk with the dog on moderate-weather days. It's actually been working out well. I enjoy having a variety of activities. However, it has made me wonder....

Why do we have to work so hard to stay healthy? It takes a lot of planning and effort to pull this off. Sometimes we're successful and sometimes we're not. What happened to our ability to instinctively do what's best for us? It's gone. We don't always eat real food, we aren't always as active as we should be, and yet it can feel so natural. Is this an early step on the path to our own extinction? Survival of the fittest is taking on new meaning.