I did a ride on Sunday with someone who has only ridden 6 miles as his longest ride. Sunday he did 49.

Difference is that the 6 miles is a one way commute- done twice a day 5 days a week. Seems that little and often will work for some. Mind you- at twenty miles he was dead---but had to do the rest of the ride to get home. Not the ideal way to up the milage but try a morning and afternoon ride for a week. Keep milage within your capabilities and you should be able to do it. But if you have to buy new trousers to accomodate the increased thigh size- Don't blame me.