Mark Appel says he is taking an "indefinite break" from baseball.

The 26-year-old is a former No. 1 overall pick.

"I don't know what the future holds. I'm pursuing other things, but also trying to become a healthy human," Appel said. "I'm 26, I have a Stanford degree, I have many interests beyond baseball, which I still love, but I have a lot of things I care about. I enjoy challenging my mind. My last four years in baseball have challenged my mind."

The Houston Astros selected Appel first overall in 2013.