Carrie Underwood works out hard to prepare for her "physical" performances.
The 'Jesus Take the Wheel' hitmaker likes using her "whole body to sing" so she has to keep it in tip-top shape.
The 39-year-old country star told PEOPLE magazine: "I'm a very physical performer in that I feel like I use my whole body to sing. I don't sing easy songs, and I don't want to. So I have to keep up with myself."
Carrie - who has six year-son Isaiah and three-year-old son Jacob with her husband, former hockey player Mike Fisher, 41 - thinks it's important to maintain her strength to give the best show and her "all" while on stage.
She said: "I'm 39 years old now. I have to make sure that I can give the fans the best show that I possibly can and feel good doing it. I don't want to feel exhausted when I get off stage … I want to be ready for it, and I want to be able to give it my all."
The 'Before He Cheats' hitmaker thinks "things are easier when you're in your 20s".
Carrie said: "Things are easier when you're in your 20s. You feel like you can do anything. You probably can. I feel like I'm a little more conscious just about my body and not overdoing things."
The Grammy winner sees exercise as her "therapy" and starts each session in the same way; walking on "the treadmill for 10 to 15 minutes".
She said: "I'll walk on the treadmill for 10 to 15 minutes, because I feel like if I do the same thing before I work out, my body's going to be like, 'Okay, we're about to work out'. In my brain and in my body, and I'm telling my body I'm about to work out."