The Male Supporting Lead Is Hard to Pair (Cultivation)

I wanted to write this story after reading Cat Doesn't Behave's Good-for-Nothing Female Side Character's Cultivation Notes, so if any of you see the shadow of a familiar character in my story, that's perfectly normal. In his previous life, Lu Guo was a white-bearded old man who had cultivated for over three thousand years and reached the peak of the late Mahayana stage. As he ascended, he endured forty-nine bolts of heavenly tribulation lightning. Just as he was left powerless after the ordeal, an old romantic rival ambushed him and destroyed his body completely. When the other party tried to devour his primordial spirit, he used the thunder technique he had just comprehended to drive them off, then tore open the void and fled into the unknown. In this new world, cultivation is still possible, but his constitution is pitifully weak, and he has a twin older sister who's petty and vindictive. With his primordial spirit wrapped in true essence, a good-for-nothing constitution, and no memories, Lu Guo... The rest is for you to guess