Sooner or later, I'm tired and weary and my gray hairs are not in my favor
Kendrick’s referring to the stress that he’ll be putting himself under if he were to think about death too much. It would exhaust him and would not be a benefit to him in the long run.
Then he continues his thought in the next line telling you that he really was stressing out when he wrote this verse.
To help improve the meaning of these lyrics, visit “I Hate You” by Kendrick Lamar Lyrics and leave a comment on the lyrics box