Indeed, all people need to do is move around. What was shocking for me about this study is just how LITTLE movement is needed to have massive effects! We should really all be encouraging our loved ones to get out there and move, could keep them around for years more with out even all that much more effort.
That is why gardening is so great
I think gardening helps people on a psychological level as well, there is something de-stressing about working with your hands and being with nature.