Kevin Hart’s preaching the gospel of gains — but he’s giving all the credit to his guy Mark Wahlberg … saying nobody’s doing it like the king of those brutal 4 AM workouts.

TMZ caught up with Kevin at Wally’s in Beverly Hills Wednesday — and he kept it playful, clowning Mark’s routine as “s***” before flipping it, joking the 54-year-old’s actually 75 and deserves even more credit.

Check the video — Kevin goes full fanboy over Mark’s grind, which he recently told us is so intense even Druski had to tap out when he joined him for a session.

But Kev’s not just hyping his boy — he also gets into his own health kick, showing love to the gym life and shouting out his workout circle along the way.