First, Kimmel quizzed the Democratic presidential candidate about news that broke earlier in the day of the release of additional emails from the time she served as secretary of state.
"The State Department said that they have to release 15,000 emails by — the deadline is a couple of days before the debate," Kimmel said. "Are you concerned about that?"
"No," Clinton responded. "Jimmy, my emails are so boring. And I'm embarrassed about that. They're so boring. So we've already released, I don't know, 30,000 plus, so what's a few more?"
When he asked her about the rumors swirling about her health, she offered him her hand and said, "Take my pulse."
Kimmel agreed as Clinton said, "To make sure I'm alive." He took her hand and gasped, telling the audience, "Oh, my God, there's nothing there."
She played off his words, implying that the stories are baseless. "With every breath I take, I feel like it's a new lease on life," she quipped sarcastically.
Last week during a speech about terrorism, Donald Trump said Clinton "lacks the mental and physical stamina to take on" ISIS. He also went after the length of her speeches, saying she would rather "go back home and go to sleep."
Trump surrogate Rudy Giuliani continued that attack on Fox News Sunday when he told the audience, "Go online and put down 'Hillary Clinton illness' and take a look at the videos for yourself."
Clinton called the Republican nominee's health attack a "wacky strategy" and chalked it up to the "crazy things" said by Trump and his allies.
"It absolutely makes no sense," she said. "I don't go around questioning Donald Trump's health. I mean, as far as I can tell, he's as healthy as a horse."
At one point during the interview, Kimmel asked Clinton to open a jar of pickles to prove how healthy she is.
The two also discussed how she was preparing to debate Trump.
Clinton told the late-night host, "I'm planning on drawing off my experiences from elementary school."