On the contrary, sitting is not the modern plague. It's just the scary metaphor health practitioners use to remind us to get up and move every once in a while. They recommend standing up 5-10 minutes for every 45 minutes we're sedentary.
The tagline caught on because doctors grew concerned that people weren't active enough, even kids. Instead of shooting hoops, children were playing NBA 2k inside while their parents slaved away answering work emails on their digital devices. Everyone was gaining weight and increasing their chances of diabetes and heart disease.
A watchmaker named Yamasa Tokei originally trotted out the 10,000 steps thing in 1965. He made and sold a pedometer he called Manpo-Kei, which when repeated out loud mimics the rhythm of a walk. In Japanese this translates into “10,000 step meter.” Ads for Tokei’s device said, “Let’s walk 10,000 steps a day!”
Like everything else in life, sitting is about balance. We sit to focus and meditate. We stand to manage emails and other routine tasks. Buy a standing desk if it helps or stack some books on top of each other and make your own. Walking meetings are also known to help jog the brain. Make what you want on the campaign for movement, but be careful to align sitting with smoking when the former is a more of a preference and the latter is a proven killer. Coffee, anyone?