In 1966, The Addams Family decided it was time for Uncle Fester to drop a few pounds and focus on his health.

In "Fester Goes on a Diet," casting directors called upon real-life "fitness king" Jack LaLanne, who became one of the only guest stars to appear on the The Addams Family as himself.

LaLanne was an oddity in the real world — an older man capable of swimming 1,000 miles with his hands and feet cuffed while towing a boat — and he became a popular fitness guru because of these daring displays of his unexpected strength. He published bestselling books and had his own TV show.

But before LaLanne became a health nut, he was actually a real-life Pugsley kind of kid, who told The Washington Post in 1979 that as a kid, he attempted to kill his own brother not once, but twice.

He blamed his violent temper on his poor diet.

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"I was a sugarholic by the time I was about 10," LaLanne said. "That’s all I wanted to eat: cakes, ice cream, soda pop. I had an uncontrollable temper. I tried to kill my brother on a couple occasions."

As LaLanne failed to control his behavior, he started messing up at school, too.

"I got failing grades in school," LaLanne said. "It was affecting my brain. It was affecting my intellect. I was so weak and skinny I couldn’t participate in sports. I had pimples and boils. I was wearing glasses. The doctor recommended my parents take me out of school for six months."

After being withdrawn from school, LaLanne had a turnaround when he went to visit a nutritionist who told him that his body could still be saved, if he started eating right and exercising more often.

Young Jack knelt by his bedside that night and prayed for the willpower to follow the nutritionist’s directions.

And it worked!

"By the time I was a senior in high school, I had scholarships to three different universities for sports," LaLanne said.

It was at this time that LaLanne started becoming the fitness king, helping other kids who struggled with nutrition to follow the same path he took.

"People need leaders," LaLanne said. "They need examples."

On The Addams Family, Uncle Fester became LaLanne’s next pupil, not because Fester was motivated to be strong and healthy, but because he had fallen in love with his pen pal who he was soon to meet.

Fester wanted to look good and make a good first impression.

It’s a hilarious Uncle Fester episode with a great twist that gives Uncle Fester the happy ending he sought.

LaLanne may not have agreed with everything about Uncle Fester’s lifestyle choices, but he certainly would’ve appreciated, just as fans did, seeing Fester happy and dwelling on the positive side of life by the episode’s end.

"See, happiness to me is this moment," LaLanne said. "If you have enough willpower to control yourself, you control your thoughts. ‘Cause that’s what you and I have. We have these negative thoughts that everyone has ever thought, good thoughts, bad thoughts. But if we’re strong enough to be able to weed out the bad, just take the good and dwell on the positive — then we’re working on happiness."