I know that chazal say hagadol mei'chaveiro, yitzro gadol hei'menu; but knowing my struggles, I can't even imagine that a gadol b'yisrael has anything like that going on. I believe the answer is that they struggle with the same midos, but at a more refined level. Yet, I had trouble having a concrete idea of what that really meant. Then I heard that when R' Bachaya first contemplated writing the Chovos l'Vavos, he abandoned the project. Even though he had already come to the conclusion that such a sefer was desperately needed, he didn't feel that he was the one to write it. Over the next months or years, R' Bachaya constantly questioned himself -- was he truly not at the level to write Chovos l'Vavos, or was he just being lazy? Eventually, of course, he decided that his motivation for refraining was more out of laziness than true humility.
Imagine if R' Bachaya had not continually questioned his motives! What would the world be like without his Chovos l'Vavos? Thousands and milliions of Jews over hundreds of generations could have, chas v'shalom, gone astray. When I struggle with laziness it affects a page or two of learning, but when Rabbeinu Bachaya struggled with laziness, the (eternal) lives of millions of Jews hung in the balance!