JetBlue CEO Robin Hayes is stepping down next month to focus on his health after admitting that the job has "taken its toll."

Hayes, who has been at the helm of JetBlue for nine years, will remain as a strategic adviser to the company over the coming months as part of the transition, the airline said Monday.

Joanna Geraghty, who has been serving as the carrier's chief operating officer, will succeed Hayes as CEO and take over his position on the board effective Feb. 12.

"The extraordinary challenges and pressure of this job have taken their toll," Hayes said in a statement. "On the advice of my doctor and after talking to my wife, it’s time I put more focus on my health and well-being." 

Hayes said the company has implemented a "rigorous succession plan" and he is confident in Geraghty's ability to position the airline for success.

"She guided the operation through the most turbulent time in airline history, has overseen the development and execution of new commercial initiatives, and has tirelessly worked to make JetBlue a better place for our crew members and customers," he added.

According to Hayes, Geraghty has been "actively engaged in our integration planning with respect to our proposed Spirit transaction." She has also developed a strong plan for the carrier as it tries to return to profitability.

The New York-based airline has been trying to purchase Spirit Airlines to the tune of $3.8 billion, but the deal has been blocked by regulators over antitrust concerns. 

In July, the airline said it would follow a ruling to end its Northeast Alliance with American Airlines to try and push the Spirit deal through. 

At the time, Hayes said in a staff memo that the move would "enable us to focus even more on our combination with Spirit," according to Reuters.