Answer:
"Always remember kiddo, when you're down, laughter is the best medicine."
Explanation:
According to the Oxford English Language Dictionary, a proverb is "a general truth or piece of advice."
In the given passage, we can identify the phrase "when you're down, laughter is the best medicine" as a piece of advice.
Therefore, the sentence we should highlight is: "Always remember kiddo, when you're down, laughter is the best medicine."