When Arjuna had enough mind control to perform great austerities, why does he say that he can’t control the mind?

From Promila Chitkara Mataji
Arjuna had all the rare accomplishments (e.g. winning boons from Shiva, entering heaven etc) because of the difficult austerities he performed before the war. He lived in forests to perform those austerities, fought wars etc. Then, why did he say he could control the wind but not the mind? He did control his mind otherwise he wouldn’t be able to do what he did. Moreover, he wouldn’t be Gudakesha if he had no control over mind.
Is this because the Gita was spoken for us and not so much for him?
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