Bhagavad Gita, Chapter 6, Verse 45

The Yogi, striving assiduously, purified of taint, gradually gaining perfection through many births, then reaches the highest goal.

Real progress adds up across real time, and eventually, genuine effort plus that accumulation actually reaches completion.

This closes the loop on the whole worry Arjuna raised. Nothing sincere was ever lost, it kept building, and combined with continued real effort, it's described as genuinely capable of reaching full completion, not staying perpetually unfinished.