18 years so far for me. It's been my first and only programming job too. Got hired 3 days out of school and still working for the same company.

I switched to a standing setup about a month ago. At first, I had a standing setup & a sitting setup side-by-side, so that I could have the option of sitting if I go tired. 2 weeks in I got rid of the sitting setup because I found that sitting became uncomfortable after a short period of time. Haven't lost any weight yet, but it definitely improves your digestion, and I have far fewer aches in my shoulders, neck & arms. A split keyboard is a must so that your arms can hang naturally. Some padding under the feet is nice too. Productivity-wise, it has changed my work pattern a bit. Previously, during a lengthy compile or download, I would go to email, browse, or start a "quick" game of something...which of course would take longer than the compile/download I was waiting on. Now I do a "micro" workout while waiting. ie stroll around the room, stretch, swing my arms just until the task I am waiting on is done. I definitely recommend giving it a try. Just as an aside...I also highly recommend Tai Chi. Been doing it for 3 years now...within the first 6 months it completely eliminated some severe chronic pain I used to have in my right shoulder/arm.