John_V 

I don't know how many days a week you ride, but I have been seeing some really long rides that you have been posting. You may want to try riding shorter rides on more days. I'm almost 67 and I generally ride 30 to 40 miles a day and do longer rides on the weekends. I save my really long rides for the charity events and try to do about 8 to 10 of those a year. Also trying doing more solo rides where you aren't being pushed to perform as well or better than the other riders in the group. This has worked for me and has kept me from getting burned out on riding. Maybe if it starts to become more about the ride rather than the competition, you may not feel as if you are getting burned out. This is just my opinion, for what it's worth.