The real top-line answer is to work at it. Wellness is created. There's stuff we can't control: that's the gene lottery. But we still have plenty of scope to generate the core characteristics of wellness: energy, focus and concentration. Plus a sense of lightheartedness or an ability to not take it all too seriously.
And the key? The gym? Vitamin tablets? Yoga? Possibly any of those. Maybe all of those. Possibly none of those. The key is once again to get attached to our body, both mentally and physically. To treat it less as a carrier and more of something we live with every minute of the day: notice its sophisticated feed-back systems of moods, aches and concerns. The mind/body cannot always be pampered. But it cannot always be ignored; not without serious consequences.