Jay Rosser, Pickens' chief of staff, said in an email Monday the mini-stroke happened a few days before Christmas and Pickens was hospitalized for a few days.
In a tweet he sent out on Monday, the 88-year-old Pickens said that this will be "another 'Old Man Makes a Comeback' story."
Experienced a ministroke. Will be another ?Old Man Makes a Comeback? story. Back to working in the office. I think. Kidding. More later.— T. Boone Pickens (@boonepickens) January 9, 2017
A second tweet said Pickens would reduce his schedule for the next three months and that he would be 'resting and exercising' his brain.
On my ministroke. Reducing schedule for next 3 months. Will be resting/exercising my brain just like my body. https://t.co/d4FGSqKrqj— T. Boone Pickens (@boonepickens) January 9, 2017
The tweet also included a link to a Youtube video showing Pickens running on the streets in San Francisco, set to the music of "Eye of the Tiger". The video was published in 2014.
Rosser says Pickens' speech was affected by the mini-stroke, but not severely, and he is undergoing daily speech therapy.
Pickens said in his tweet he was back working at his Dallas-based investment firm BP Capital.
Rosser said that Pickens, who made his fortune as a Texas oil producer but has also championed alternative energy forms, worked all last week and was back in the office this week.
The Associated Press contributed to this article.