I'm 42 and my dad is 69. We both have Natures Comfort GT-220s. My dad still cuts wood and is healthier now than when he didn't own one. I think the idle time during the long winter months was wearing on him and depression was setting in. He's had a wood boiler for the last 4 years and is in a lot better shape.
For me, i need the excercize during the winter months to keep off the fat! I enjoy getting outside and cutting wood!