From the Start, I Was a Deity: Why Do I Get Weaker the More I Cultivate?

[System, Cultivation, Transmigration, One Heroine] (I don’t know what to write, so I’m just messing around.) After transmigrating to a lower realm of cultivation, he starts out with the power of a Deity Transformation cultivator. A thousand years later, he’ll undergo tribulation and be able to return to Blue Star. But a thousand years is an awfully long time, so he has no choice but to find a small sect and coast through life. Only, nobody ever told him that if you don’t cultivate, your cultivation level will fade away.