When I was a kid, I was of the belief that having a horse win racing’s Triple Crown happened all the time. Secretariat won when I was 10 years old; four years later Seattle Slew won the Kentucky Derby, the Preakness and the Belmont Stakes; and then Affirmed edged Alydar in all three races in 1978.

Not realizing that it had been a quarter century between Citation in 1948 and Secretariat’s historic performances in 1973, I figured this was what the sport was all about. Well, it is. But now multiple generations haven’t seen a Triple Crown winner, and it doesn’t appear there’s going to be one any time in the near future. With prohibitive favorite Orb’s fourth-place finish Saturday in the Preakness, we’ve gone a record 35 years without a horse winning the Kentucky Derby, the Preakness Stakes and the Belmont Stakes. It appears the chances of seeing a horse accomplish that feat are dwindling.

Many years ago, breeders prepared their horses to run all three Triple Crown races. Like boxers or pitchers, horses worked a lot. They were prepared to run long distances, so the Kentucky Derby was easy at a mile and a quarter. The Preakness was a step up at 1 3/16 miles, and horses were trained to run the Belmont’s 1 ½ miles.

But, like other sports, horses have become coddled and unprepared to work long hours. As an example, in 1973, when Secretariat won his Triple Crown, Muhammad Ali fought four times. He defended his heavyweight title, lost it, won it back and then defended his new title. Wilbur Wood led major league baseball with 359 1/3 innings in 48 starts, and Jack Billingham and Steve Carlton tied for the NL lead with 293 1/3 innings in 40 starts apiece.

That same year, Secretariat won, placed or showed a dozen times. In two years, he raced 21 times, including those 12 times as a three-year-old in 1973. That’s just the way it was.

By comparison, last year the current world heavyweight champion, Wladimir Klitchko, fought three times. But he had a more normal schedule in the years before that: one fight in 2009, two in 2010 and one in 2011. He’s fought seven times in the last four-and-a-half years. In 1972 and ’73, Ali fought 10 times. The MLB innings leader last year was Justin Verlander with 238 innings, 121 innings fewer than Wood in 1973, and three pitchers tied for the major league lead with 34 starts, 14 fewer than Wood.

Last year’s Kentucky Derby winner, I’ll Have Another, was retired before the Belmont Stakes because of a tendon injury, so it’s unfair to compare his workload to Secretariat. The year before, Animal Kingdom ran five times. For his entire career, Animal Kingdom ran 11 times, one fewer race than Secretariat had as a three-year-old.

So today’s horses, which are quite expensive, are prepared more to win one race and be retired to stud than to win all three Triple Crown races. Like pitchers, they are investments that are treated with kid gloves, with no plan to stretch them out and have them play on a regular basis.

For that reason, it’s unlikely we’ll see another Triple Crown winner. Affirmed may have been the last. Our chances of seeing a 300-inning starting pitcher or a heavyweight boxer who fights 10 times in two years are just as good. What do you think the chances of that are?