CHICAGO (CBS) — Illinois Gov. JB Pritzker has sustained a hairline fracture to his left femur, his office confirmed Thursday.

The governor is now under a doctor’s orders to rest and recover for the next four to six weeks.

Pritzker’s office says he is “in good spirits” and will be receiving frequent daily updates from his staff.

“He will be fully engaged in conducting the business of the state,” his office said in a release.

Pritzker sustained the injury to his leg “some time ago,” his office said, but he is not certain what caused it.

It has become worse in recent weeks as he attended events, including both state fairs, where he walked or stood for significant amounts of time.

The fracture will not require surgery, officials said, and he is otherwise in good physical health.