not assuming your physical condition, have no idea if you work out or not, but still wondering if you think sedentary IT career has contributed to lack of physical fitness?
I like IT work, I love being in the command line building servers, instances, writing shell scripts. Quite a few of my friends have moved up into management and to a man, I think they are miserable--what with dealing with multiple personalities every day, plotting peoples' time off, ensuring on-call coverage, living in meetings. I fancy none of that.
My fear is that within a couple of years I'll be 50 and still a sysadmin. Now, having said this, I don't find the work belittling or "less than". My wife, thankfully, is in full support of whatever I undertake as long as I do my bit to provide financially to the household. She has encouraged me more than once to strike out on my own and do my own thing. Like most people, I'm terrified to fail, so I sit and do nothing, wondering why the status quo sucks.
one thing you might consider is option of becoming a consultant and having your existing company be your first client. then you'd have more flexibility to explore other options with either other clients or side projects. don't know if that's possible in your organization, but you might be surprised, it could be a win-win for both you and them.