Blake Shelton reveals why he's not competitive with wife Miranda Lambert

LOS ANGELES, CA (KTRK) -- Blake Shelton and wife Miranda Lambert are considered country music royalty. They're both at the top of their game, topping the charts and raking in the industry's top awards.

But are they competitive?

Shelton told Jimmy Kimmel last night that he's not competitive with his spouse. Why?

Find out in the video below. It just might have something to do with his health...