Tim McGraw is just about done with his 2013 Two Lanes of Freedom Tour, closing out the successful trek on Saturday, July 27 in Virginia Beach. He is no stranger to living on the road, so over the course of his career, he has had plenty of experience adapting to the lifestyle. What's the one thing that he can't live without while on tour?

Exercise. The 'Highway Don't Care' singer must be able to work out while traveling from city to city.

While many artists list their iPads or iPods, a vast DVD collection or a good book -- or even an endless supply of socks and underwear -- as survival essentials for tour, McGraw needs exercise, since it keeps his body, mind and his voice healthy and strong.

"I think that's what sort of keeps me functioning and feeling like that I’m ready to go," the star reveals (quote via Big Machine). "I think it keeps my voice in a good spot. I just think that it mentally keeps me focused. So I think working out is probably the mainstay as to what I really need on the road."

McGraw, 46, is in incredible shape since he does CrossFit training -- which combines cardio with lifting and strength training -- and his dedication and commitment to working out shows every time he posts a picture on Twitter.

McGraw's workout regimen is so intense that it even sparked fear in his tourmate Brantley Gilbert, who shared his "anxieties" when we spoke to him.