Joseph Baena was out Wednesday in Malibu -- near his Pepperdine campus -- when our photog wanted to know if he'd follow in his father's footsteps. Our guy even tossed up a softball: if he could reboot one of his dad's old movies, which one would it be?

Gotta hand it to Joseph ... for not only entertaining the question but also sticking to what's working for him -- pumping iron like his pops.

Joseph also gets in plenty of cardio with his bros ... Pepperdine style, of course.