Carrie Underwood's BIGGEST fitness secrets revealed

Carrie Underwood may have once sang for Jesus to take the wheel, but the country superstar is in full control when it comes to her fitness routine.

The 40-year-old "is the most dedicated, consistent human being," Carrie's trainer Eve Overland told outlets while promoting the duo's partnership with Bodyarmor Lyte. "She puts in 100 percent of her entire being into everything she does, in or out of the gym. She's very focused, motivated and she's always in a good mood."

Eve explained that their sessions have evolved over the 13 years they've worked together, although the focus is always on strength training. "She's at that point where she's so completely sculpted and conditioned," Eve said. "So now I'm working on the detail."

During their 90-minute workouts, Eve will guide the Before He Cheats singer though basic compound lifts, including squats, deadlifts, rows and presses, "because they work and they give you the most bang for your buck, no matter what age you are."

Having turned 40 on March 10, Carrie's focus is on mindfulness when it comes to movement. "Is it going to take us through our day to day life as we grow older, to pick up groceries, to lift up your children?" Eve shared. "What is going to keep us in the game as long as possible?"