T. Boone Pickens, a titan of the U.S. oil patch, on Thursday said his health is deteriorating following several strokes, but he remains "mentally strong" and will keep working.
Pickens, founder and chairman of BP Capital, penned a post on LinkedIn titled "Embracing (or Accepting) Mortality" after suffering what he called a "Texas-sized fall" last week that required hospitalization.
"Just a year ago I felt immortal, wearing my age with pride, even joking about it," Pickens wrote.
"But things have changed for me since the strokes. I clearly am in the fourth quarter, and the clock is ticking and my health is in decline, much as it is with others in my stage of life."
Pickens, 89, rose to prominence as the chief of Mesa Petroleum during a feverish period of corporate takeovers in the 1980s. After retiring at 68, he formed the energy investment firm BP Capital, where he made his first billion dollars.
Since then, he has remained a closely followed oracle of energy markets.
In December, Pickens had several strokes, necessitating therapy that he says allowed him to regain about 90 percent of his speech. Following last week's fall, he said it is "hard to find the words I'm looking for to speak clearly," though he comprehends information clearly.
"Speech therapy will fix that, I'm confident," said an optimistic Pickens.
"Just as I exercise my body daily I will exercise my brain and continue with rigorous speech therapy to regain what I can. I am always up for a good challenge."
Despite the recent setback, Pickens said he is determined not to leave work.
"I remain excited every day, engaged and thrilled in the office and on the road. I thrive on that activity, and I'm going to stick to it, no matter the setback," he said.