Hey,
I'm soon to be 57 and I did my first Century ever, today. Someone told me that a Century is 2 halves, the first 80 miles and the last 20. Today, that statement became clear except for me it was more like 75 and 25. The 25 miles seemed to go on forever. I can see it is very easy to overestimate what you can do when doing a Century. The 75 mile portion was very easy while the 25 was gritty with the last 10 being pretty tough. I did finish though at what I felt was a good pace, 61/2 hours at 15.3 MPH. Lot's of rolling hills and some headwinds too plus climbing temps took a toll. I have been working towards this for a while and just wanted to tell somebody. Thanks.

http://www.endomondo.com/workouts/m0w1D9-lnOo