Paul Alexander, who contracted polio as a child and was confined in an iron lung, died Monday at a Dallas hospital at age 78, his longtime friend said . He said Alexander had recently been hospitalized after being diagnosed with Covid-19, but he did not know the cause of death.

Alexander managed to train himself to breathe independently for part of the day, earned a law degree, wrote a book about his life, built a huge following on social media and inspired people around the world with his positive outlook.

In 1952, at age 6, Alexander contracted polio. Paralyzed from the neck down, he began using an iron lung, a cylinder wrapped around his body with air pressure in the chamber forcing air in and out of his lungs. His TikTok account has millions of views.

“He loved to laugh,” Spinks said. “He’s just one of the biggest stars in the world.”

In a “Conversation with Paul” post on TikTok, Alexander told viewers that “positivity is a way of life for me,” with his head resting on a pillow and the whirring of an iron lung heard in the background.

Spinks said Alexander’s positivity had a profound impact on those around him. “Being with Paul was an enlightenment in many ways,” Spinks said.

Spinks said Alexander had learned how to “breathe air into his lungs” to get out of the iron lung for part of the day. Spinks said Alexander can type on a computer and use a cell phone with a stick in his mouth.

“As he got older, it became more difficult for him to breathe outside his lungs over a period of time, so he actually just retreated into his lungs,” Spinks said.

Gary Cox, who has been Alexander’s friend since college, said his friend always smiled. “He was very friendly,” Cox said. “He was always happy.”

A book Alexander wrote about his life, “Three Minutes with a Dog: My Life in an Iron Lung,” was published in 2020. Cox said the book’s title came from a promise Alexander’s nurse made to him as a child: “If he could learn to breathe on his own for three minutes, I would get a dog.