I always tell people who are new to cycling not to ride more than 30 minutes a day for the first week. It takes a month or two to build up to using the bike to for transportation--- more to get used to hauling heavy loads after shopping.
The trouble is that most of us here live in the fast food nation-- we want things now! and we're not very good at any long term, slower paced lifestyle plan, like cycling.
I bet a could write a real neat article about flunking out of Med School in a week-- because becoming a doctor is really, really hard.
Cycling, like most things that are worth doing, takes commitment and time.