I used the century training schedule listed above and completed my first century last weekend. There are two things that helped me finish.

1. 120 miles per week training. (I didn't do the 60 miles as suggested, but I would do two 30 miles rides in a day)
2. Group riding. Having someone else to pace with on your ride does make a difference.

Oh, the worst is mile 80 through mile 90. Mentally, you think, I could just sag, 80 miles is enough. But after 90, you think, just 10 miles to go. It is all mental.