Tom Arnold can finally tuck his shirt in, and he’s letting the world know!

The actor reveals that he lost 89 lbs. since the birth of his son Jax last April after realizing that he needed to be around for his son when he was older.

"Something inside of me changed," the 54-year-old said of becoming a dad. "I knew I needed to live as long as I could."

The “True Lies” star can especially appreciate the blessing of his son’s birth after he and wife Ashley, 38, struggled through years of infertility issues.

"The moment I saw [Jax] I realized he deserves the best," Arnold says. So the dieting and workouts began.

At his heaviest, Arnold weighed around 287 lbs. A typical breakfast would consist of a six-egg omelet with cheese, six turkey sausage links, and oatmeal.

For dinner, an extra-large meat pizza along with breadsticks dipped in cheese. Plus, 15 diet sodas throughout the day!

tom arnold

Arnold this past April

"There was a lot of shame," Arnold admits. "One time I had a tailor come over and sew the weights into my suits – this is what you wear when you are 210, 220, 240, 300. That saved me the time of going into my closet and getting so upset and frustrated."

After Jax arrived, Arnold gave up bread and cake right off the bat. He also made cardio, circuit-training, and abdominal workouts a priority.

But the actor’s favorite exercise? Goofing around with his 8-month-old. “I have tons more energy to play with my son," he tells PEOPLE magazine.