Despite getting off to a rocky start, the two soon realise that there's a lot they can learn from each other.
Though the film has many chuckle-worthy moments, it is more of a dramatic role than Hart has tackled in other movies. He told Good Morning America, "It was a great challenge, I wanted to show the world that was another level to me and my acting talent ... I think it's my best work to date, honestly."
The Upside, which also stars Nicole Kidman, opens in cinemas on February 8.
