T. Boone Pickens, who recently suffered from a series of strokes, took a "Texas-sized fall" that put him in the hospital last week.
In a posting to LinkedIn, the corporate raider and legendary oilfield wildcatter said that he is still mentally strong but that as far as his life goes, "I clearly am in the fourth quarter."
Pickens, the founder and chairman of the Dallas investment firm BP Capital, suffered several strokes over the holiday and has been undergoing speech therapy. The 89-year-old said he's regained 90 percent of his speech through aggressive therapy and determination.
"Many of those who face adversity like this at 89 choose to hide it," he wrote. "My life has always been an open book. Some chapters of my life have been great. Others not so much."
The fall, he says, is just a set-back. Pickens said he can still comprehend and process information well, but has difficulty speaking clearly. He remains upbeat about the future.
"That's the way to approach life. Be the eternal optimist who is excited to see what the next decade will bring," he said.
Pickens built one of the country's biggest independent oil companies, Mesa Petroleum, before moving on to BP Capital and founding clean transportation fuels company Clean Energy. He's also given away more than $1 billion to philanthropic causes, according to BP Capital's website.