The CEO of United Continental Holdings, Oscar Munoz, is recovering well from a heart transplant operation.

It has been nine days since Munoz needed to have the surprise operation, and now Munoz is well enough to leave the hospital and return to his home in Chicago, according to a Wall Street Journal report.

In a letter to employees released by United, Munoz said he felt “as strong as ever,” and that it won’t be long before he’s back to work.

Munoz, 57, had a heart attack in October, six weeks after being annointed the head of United Airlines, the No. 3 airline in the United States. In the meantime, former general counsel Brett Hart has been leading United as Munoz recovers.

Munoz will likely return someone time in the beginning of the second quarter, a delay due to the heart transplant operation.

“I know that a lot of you spent time away from family and friends these past few weeks getting our customers home to their loved ones. Thank you,” Munoz wrote in the statement. “Your hard work in the face of challenging conditions was exceptional, and our customers noticed. I couldn’t be more proud of what you did and am pleased to share that we received our highest customer satisfaction performance for the holiday period in more than three years! It’s a fantastic achievement.”

He added: “As I thought about my return, I gave careful consideration to what greater things we can do together, and that has spurred my recovery. We’ve made a lot of positive changes these past few months thanks to your efforts. Take pride in these accomplishments and our success. Remember, even better days lie ahead if we stay focused on consistently earning our customers’ trust. Keep up the great work, and I look forward to seeing you soon.”