How Hard and how long did it take you to be a professional runner?

[The following answer is from a 2004 Olympian / pro track athlete in response to your question]

Becoming a professional runner isn't easy, but it is possible. Generally runners need 10 - 12 years of dedicated, year round training to develop the strength and technique to compete at a professional level (means that most professional runners tend to turn pro between 20-25 with some exceptions a little earlier or later). The US NCAA University system is widely acknowledge as the strongest training ground for professional runners in the world. Because there is no team in professional running, it is up to the athlete to be dedicated and disciplined on a daily basis both on and off the track no matter how they feel. Professional runners generally make their money from small shoe contracts and lots of performance bonuses based on placing at international competitions - the bar is high, the road is long, the window is short and the money is low for all but the top 1-3 athletes in each event / race. On the other hand, nothing beats the Olympic rings.