It was why he was left in training as a 4-year-old when the majority of his classmates had gone off to the breeding shed.
It was why he endured a grueling trip to Dubai and then returned to set his sights on breaking a North American record.
With every obstacle Curlin faced, his connections reminded everyone that the goal for the son of Smart Strike was to earn a place in the annals of Thoroughbred racing.
And as with most of the tasks he attempted, Curlin once again has emerged victorious.
A season spent chasing history culminated with another milestone for Curlin on Monday night when he became the first horse since Cigar (1995-96) to win back-to-back Horse of the Year honors during the Eclipse Awards. The ceremony was at the Fontainebleau Miami Beach in Miami Beach, Fla.
Although many expected the battle for Horse of the Year to be a dogfight between Curlin — who captured the prize as a 3-year-old last season — and undefeated filly Zenyatta, the final margin went down as another open-length victory for the muscular chestnut colt.
Curlin received 153 first-place votes to 69 for Zenyatta with dual classic winner Big Brown snagging 13 votes.
"Racing is blessed to have such a magnificent athlete among us," majority owner Jess Jackson said of Curlin prior to the Breeders' Cup in October. "He's brilliant, durable and always shows up, always gives his best. The only time he's been beaten really is when race tactics or his own physical condition prevented him from winning."
As expected, Curlin and Zenyatta were named champion older male and champion older female, respectively, with Big Brown taking champion 3-year-old male honors.
Although he finished fourth in his final career start, the Breeders' Cup Classic, Curlin put together another tour de force season in 2008.
The seven-time Grade I winner started his year in the heat of Dubai, winning the Jaguar Trophy while carrying 132 pounds and then coasting to a 7¾-length victory in the $6 million Dubai World Cup in March.
The taxing journey took little out of Curlin as he returned in June to notch a handy 4¼-length win in the Stephen Foster Handicap at Churchill Downs.
That victory prompted Jackson and trainer Steve Asmussen — who picked up his first Eclipse Award for champion trainer — to try Curlin on the turf in hopes of a possible trip to France to compete in the prestigious Prix de l'Arc de Triomphe.
Those plans were abandoned after he finished second on the grass in the Grade I Man o' War Stakes at Belmont in July. Curlin still made history when he won the Grade I Woodward at Saratoga and then took the Grade I Jockey Club Gold Cup to become North America's all-time leading money earner with more than $10 million.
While Curlin now has four career Eclipse Awards, Zenyatta picked up her first for herself and owners Jerry and Ann Moss. The daughter of Street Cry has been flawless in her nine career starts and won four Grade I races last year, including the Breeders' Cup Ladies' Classic.
"I seem to never get close to the bottom. Every time I ask her there is something there," jockey Mike Smith said of Zenyatta.
Just as Zenyatta was a virtual lock to win older female honors, so were Midshipman and Stardom Bound, who took home champion 2-year-old male and champion 2-year-old female, respectively.
Midshipman won the Breeders' Cup Juvenile, while Stardom Bound romped in the Breeders' Cup Juvenile Fillies.
Proud Spell was named champion 3-year-old filly. Indian Blessing, the champion 2-year-old filly a year ago, earned another Eclipse honor, this time for champion female sprinter.
Benny the Bull, winner of four starts last year before being injured, won champion male sprinter.
In one of the more hotly contested divisions, Breeders' Cup Filly and Mare Turf winner Forever Together bested Breeders' Cup Mile winner Goldikova to claim the honors for champion turf female.
Conduit was named turf male champion, and Good Night Shirt was champion steeplechase horse.
Frank Stronach had another banner evening. His Adena Springs was named champion breeder for a record sixth time, and his Stronach Stables edged out IEAH Stables by one vote to earn the champion owner award for a fourth time.
Garrett Gomez earned his second Eclipse Award for champion jockey with Pascacio Lopez taking champion apprentice jockey honors.