WATCH: Hillary Clinton Reacts to Kids’ Letters on ‘Jimmy Fallon,’ Gives Health Update

Hillary Clinton, Jimmy Fallon, Tonight Show guests

(Andrew Lipovsky/NBC)

Jimmy Fallon welcomed Hillary Clinton to the Tonight Show Monday night by wearing a mask to make sure he didn’t contract pneumonia during his interview with the Democratic presidential candidate. Even after high-fiving Clinton, Fallon used hand sanitizer, which caused Clinton to break out into laughter.

Clinton assured Fallon that she’s not contagious and is feeling much better. After that, Fallon moved on to more serious subjects, like letters from children. It was in reference to the Letters To Hillary Tumblr.

Fallon asked Clinton if she ever dreamed of being president as a little girl, but she said no. “It wasn’t even within the realm of the possible for little girls back then,” Clinton said. “And that’s what’s so exciting about this campaign because we have slowly but steadily knocked down all the barriers.”

Clinton then called Donald Trump‘s refusal to consider President Barack Obama an American for five years “sickening.”

The conversation turned to campaigning, with Fallon asking Clinton to explain how she can balance positivity with being serious.

Monday night’s Tonight Show also featured a performance from Ariana Grande.