HOUSTON -

As Texans training camp rolls on, the learning process never stops for Case Keenum.  The new offense, although complex, is quarterback friendly.

"One of the things coaches do is try to push your limits and make you uncomfortable a little bit," Keenum said after practice at NRG Park.

"The more you do it the more comfortable you feel being uncomfortable if that makes sense."

Saturday night in the Texans preseason opener at Arizona Keenum will get plenty of playing time to prove he's a fit.

"You know there is a sense of nervous excitement. It's not nervous scared but nervous excitement. Ready to get out there and play," added Keenum.

The underdog role has followed Keenum throughout his high school, college and NFL career. Yet, he's always answered the bell when the odds have been stacked against him.

"Any challenge you have been through at the time feels like one of the biggest ones you have gone through," said Keenum.

With Ryan Fitzpatrick holding on to the starting job for now, Keenum continues to press on.  In his eyes the battle is far from over.

"I have been through a lot and each situation makes you a better person and a better player.  If you attack each one with everything you've got I think things will work out and make you a better player."