The Derby is a race restricted to 3-year-old horses and is held 
in the spring of their 3-year-old season.
A horse in the spring of its 3-year-old is comparable to a human
teenager, around 16 to 18 years old.
Teenagers should not be pushed too hard.
Horses do not become fully mature, both physically and mentally,
until the spring of their 4-year-old season.
However, people often make winning the Derby their ultimate goal.
For the horse, the Derby is merely the starting point of its racing career.
I believe that people need to move away from the idea that the Derby is
the be-all and end-all of horse racing.