Maybe Everlasting Immortal Firmament? The MC is really old and not in the best shape to be cultivating, but does so anyway.
Buddy. You’ve been here for about two years and that’s all you can say. You must have seen others ask similar questions. That question is so vague it leaves me speechless. More info please.
it's not a novel but this story on royal road should fit your description https://www.royalroad.com/fiction/17242/adventures-of-an-old-dreamer
Not the MC itself but in Renegade Immortal, he gets enlightened seeking the Dao and asks all living creatures on the planet 'what is Dao' and this old philosopher that's famous in the mortal world but near death starts thinking about it, later on he finds an answer the MC found useful. The part where he becomes obsessed with his own search for Dao and sets out to find MC on his mountain was pretty emotional for me.
I don't understand people who make threads asking for help and then just disappears. Like come on, the first reply was 3 minutes after you made the thread, and the last reply was like 10 minutes after, and there's no reaction. Atleast be a bit invested when you ask for help