Maybe this is cheating, but what I do in a situation like that is that while I'm sitting in the chair waiting, I just lift my legs up and back for a few minutes. Of course, it doesn't embarrass me to do this in a waiting room full of people. :) If it's a long wait, maybe go walk around the parking lot or up and down the halls for a few minutes. If anyone asks, tell them you have leg circulation issues and can't sit for long periods of time. That usually shuts them up. Hey, I'm sneaky, but some days, that's all I can get in, so I have to do what I have to do.
Plus, you can do things like this right in your chair at home in front of the t.v. I whittled a few inches off my waist once doing leg lifts while I was sitting in a recliner watching t.v. at night. It doesn't have to be strenuous exercise, just move.
The way to get re-started is just to start. Not easy, but once you're started, it's not so hard.
Heading to Healthy One Day at a Time!