Your Guitar Fingers!
Make sure that your fingertips are correctly calloused. It will take time before your hands and fingers get used to the feel of the guitar. But after weeks of playing the guitar you’ll realize that your fingers and hands will no longer hurt, and you’ll be able to strike a chord without feeling pain. In summating, learning how to play the acoustic guitar, most importantly the steel-stringed version, will take some time and patience. Practice makes perfect, so remember that investing in your acoustic guitar practices will definitely make you a better musician.
The more you practice, the faster you will get these callouses. If you need help with practicing, then I suggest Learn and Master Guitar.