"The predominant feeling is a great sense of relief that the 18-hour days and the 24/7 weeks month after month have come to an end," Hart told ABCNEWS.com. "It's a much harder physical and psychological investment than most people realize -- it's very, very hard work."
And while other politicians in his shoes may have mourned the absence of attention from supporters and a secret service detail, Hart welcomed his newfound freedom.
"For six or eight months, I'd never drive a car because of the secret service protection, and getting behind the wheel was kind of a shock," said Hart of his post-election life. "You don't have people standing outside your door every night or opening the car door for you or going through crowds with you.
"It's not a decompression in a bad sense but just a change in lifestyle -- and a very welcome one," he said. "I was [relieved] to get out of the limelight."
Hart added that, in retrospect, he always considered his campaign to be somewhat of a miracle. An unlikely candidate from the start, Hart's campaigns went further than expected, and so his loss was less of a surprise than Clinton's may have been to her.
Hart said he suspects that after being the Democratic front-runner for quite some time, Clinton may feel a greater sense of defeat following her loss than he did.
"I think it would be harder to start out way ahead and to not to succeed than to start way behind and almost succeed," said Hart, comparing his own campaign with Clinton's. "To start out with all advantage is very much harder than being a dark horse."
But Dukakis, who is now a public policy professor at Northeastern University in Boston, said that politicians know what they're getting themselves into -- whether the outcome is disappointing or satisfying.
"I'm sure [Clinton] is feeling great disappointment, but on the other hand we're all big boys and girls," Dukakis told ABCNEWS.com. "We know when we run that you can either win or you can lose."