Guru can definetely make us change our opinion, and destination, if only, we turn out from manmukhs and become Gur-sikhs.
So the key for that desired transformation within us, is only, when one gives oneself totally to Him.
And giving oneself to Him totally is understanding what Guru Jee tells us through the Bani, and to follow it implicitly.
That´s it.
Then work diligently and honestly on it.
So what is that to be done?
Gurbani says: Ik Oankar Satnam, Satgur parsad Jap.
There is only one True Lord Satnam/Wahiguru/Akal Purukh, who is realized by His grace when we do His simran/jap.
Prabh ka simram sabse oochaa
Prabh ka simran man kee mael jaae.
Prabh ka simran, garb na vaseh.
The whole of Gurbani is nothing, but mahima of One wahiguru Akal Purukh and His true bhakti.
Stay blessed.
Sat Sree Akal.