Longevity Martial Arts: Grinding Experience in the Chaotic World

[You have transmigrated, named Gu Sheng, and are a farm boy.]

[This is a dynasty in chaos, where demons and monsters lurk and bandits run rampant; as someone at the bottom, you face hellish survival difficulties.]
[You decide to lay low.]
[You awaken a mastery panel.]
[You breathe a sigh of relief, you can start grinding.]
[You grind Chopping Wood to Perfect, chopping bones and breaking tendons with ease.]
[You grind archery to Perfect, becoming a godlike archer who can hit a louse at a hundred paces.]
[You learn the Iron Stone Fist, set foot on the path of a Martial Artist, and grind it to Perfect, with punches as heavy as a million pounds.]
……
[You learn the Longevity Eternal Youth True Art, greatly extending your lifespan, giving you more time to grind, and greater hope to lay low.]
……
[You grind to the limit, steadily laying low, and one day you suddenly realize, you are invincible.]