The Unsolved actor took to Instagram to show off a slow-motion video of his 4-year-old son, Axl, whom he shares with his ex, Fergie, on his first day of tee-ball. Duhamel fittingly hashtagged the clip with "#CutestThingEver."
ET recently caught up with Duhamel to chat about his latest big-screen role, playing the father of a closeted gay teen in the heartwarming coming-of-age story, Love, Simon.
"He's that dad that's always sort of takes the joke one step too far," Duhamel said of his character. "I can really relate to that because I've been known to do that myself."
The 45-year-old also admitted that having a son in real life helped inform his performance.
"Now that I'm a dad -- that obviously helps -- but there's a scene in particular where he sort of has a conversation where he talks about... 'Listen, I'm sorry if I ever said anything or did anything that made you feel uncomfortable, but I love you no matter what,'" he said. "And I think that's really what any guy or any parent can learn from this."