The hardest part is defeating EGO, and knowing that if you don't try new stuff, you will never improve. However in the process of trying things new, people are going to submit you and talk shit about you.
As a judoka coming to BJJ, i really had a bad guard game because i was always aggresive on the ground, and when in defensive positions i simply stalled.
When i played aggresive i was pretty much at the level of the top students and could win by points against the instructor, but then he told me i had to work on the game off my back.
Everyone passed my guard in 1 second, and then i was always down, i improved but lowly, i latter knew they said at my back that "Everyone rapes me", but i lol'd because in Judo i had learned to be humble and to always learn, im pretty sure these guys who said that would eventually hit a wall when they face stiffler competition, and occasionally i reverted to my aggresive top game and gave them a rough trip.