I saw my first standing desk + treadmill combo a few years ago in a friend’s office. He and his brother had both switched over to such a setup after reading about it online, and were now averaging six miles or so a day of slow-paced walking while on their computers. I thought it was pretty neat, although a bit impractical as far as space needed and costs incurred (they had developed their own solution instead of buying a pre-built model online).
Nowadays the cost has come down, and more and more people are giving treadputer setups (as they are commonly called) a chance. There are some things you should know before switching over though, especially if you are coming straight from a sitting desk setup: