Bhagavad Gita, Chapter 6, Verse 33

Arjuna said: This Yoga which has been taught by You, O slayer of Madhu, as characterised by evenness, I do not see the possibility of its lasting endurance, owing to restlessness of the mind.

Arjuna says out loud what a lot of people quietly think, this all sounds good, but genuinely doable?

This is a real, honest pushback, not disrespect. Everything described so far sounds worthwhile, but Arjuna's own experience of his own restless mind makes the whole picture feel out of reach, and he says so directly.