Douyara Watashi no Karada wa Kanzen Muteki no you desu ne

On her deathbed, a sickly young girl wishes to be reborn with a strong body that will never succumb to anyone or anything. Lo and behold, her wish is granted! Upon reincarnating into another world as Mary Regalia, she discovers her new body has maxed-out attributes, from physical strength to defense—even magic. But wait! That isn't what she really wanted! All she longed for was a normal life. Baffled by God's choice to grant her wish in this most unexpected way, Mary tries to spend her days as uneventfully as possible. The hitch is...nothing's harder than living a normal life when you're absolutely invincible!

(Source: J-Novel Club)