I Worked Too Hard to Get Back to the Top

Tianchen Immortal Lord Ling Chen, his life span is about to expire and his cultivation is completely useless. Before he died, he asked his junior sister for double cultivation, but he only wanted to do it before he died. Unexpectedly, one night later, the system was activated and life span skyrocketed! So it turns out that dual cultivation can extend your life and become stronger? In order to return to the top - I worked too hard!