And sometimes you find something that you love just as much as cycling.
Plus, change is good for our bodies. At least for me, the older I get, the more i need to "fool" my body by doing different stuff it to stay at the level of fitness I want. Not necessarily more, just different. I wish I had done this a bit more when I was teaching fitness classes in my 30s and 40s. I set myself up for some nice over use injuries.