06/11/2014 AT 02:00 PM EDT
In Wish I Was Here
, Mandy Patinkin
plays Zach Braff
's father – a fitting role for the dad of two.
Patinkin, 61, has learned a lot from raising sons Isaac and Gideon, wisdom he's sharing with fans in a special Father's Day clip promoting the upcoming film.
"Get in shape, so that when you wear the Snuggie, your back doesn't go out," he says, adding that when preparing for a baby, "Do not miss the birth under any circumstances whatsoever."
As for the dirtier side of parenting, the Homeland
star sagely suggests loving every moment.
"Enjoy changing the diaper. Don't be afraid of it," he says. "It's the greatest thing in the world. I mean, who cares if they s--- all over you?"
It's safe to say Patinkin knows a thing or two about fatherly love. After all, his role as the vengeful Inigo Montoya in 1987's The Princess Bride
catapulted him to fame with the ever-quotable line, "You killed my father. Prepare to die."
Wish I Was Here
, directed by Braff after a Kickstarter campaign
and also starring Kate Hudson
, hits theaters July 18.