I'm 64 and have been riding faithfully since my retirement 9 years ago. I do about 150 a week and ride several centuries a year because that is what gives me a constant goal. Until VERY recently, I rode 5 days a week, no matter what. Within the last several months (due to a saddle sore and some antibiotics that reduced my weekly riding) I discovered that resting 2 days after a hard day of hills or a long ride makes me improve and feel 200% better. In the last 3 months, I have improved more than the last 3 years! Maybe it's an age thing! My problem has been that I really enjoy riding and hate taking days off! Bottom line, the older I get the more rest I need to recover and improve!