Talking about improving the culture, I prefer to say "develop" or "evolve" rather than "change". If I walk into a room and say: "we are here to change the organization," it sends shock waves through the group. If I say: "your success to date has come from who you are, to be successful in the future, we need to get to X, let's talk about how we evolve the organization to that point," that is a very different statement. Successful organizational "change" must come from the people. So, recruit them with common purpose, recognize that it will take time, and plow forward.