I hear a lot about people feeling stiff (No, not like that. Get your mind out of the gutter!). There are at least two things going on there, and we often have some confusion about a couple of common terms. I’m going to explain.
Flexibility is about muscles. When our muscles feel stiff, we need to stretch them. This happens when we are stuck in a chair for too long or we do a bunch of exercise and don’t stretch afterwards to help our muscles recover from all that contracting. Flexibility is a learnable skill, although there will always be folks who are more flexible than others.
Mobility, on the other hand, is about bones and joints. As we get older, mobility can be affected by things like osteoarthritis. We want to preserve as much mobility as we can and the way we do that is to take our joints through their full range of motion pretty much daily. Mobility is a lot more structural, but we still can help it along by working on our flexibility and by continuing to move.
Bottom line: moving is still good. Go play.