Well though I will be somewhat elusive I will dismiss the 10,000 hour theory and state that I am one of the genetic guys. The guys in the 33 know better but I don't come to this side all that often.

Quick history:
Became a Cat 1 in less than a full season at the age of 18, my first year racing. Had the opportunity to race for a pro team in Belgium a few years later, got hit by a car and stopped racing.
Started riding again many years later after having spent time in a bunch of other sports never having ridden (10+ years). Began riding again at a weight of 241 pounds and within a month and a half did my first century (fund raising thingy) - pulled a group of what started out as 20 (mix of racers and fast club riders) for the first 75 miles before they all got dropped - finished on my own in under 4:45. Was a Cat 1 again by the end of the year (started racing in June).
Although I am sounding arrogant it is the truth and I do believe that to get to the elite level you need something more than 10,000 hours. People must set realistic goals. Like others have said if it takes you a year to go from Cat 4 - 3 - enjoy it for what it is, a hobby, have fun.
If you go from Cat 5 - 1 in a year - set your goals a little higher