There's a big difference between those who lead a successful change and critics who simply theorize about it.
It's important to accept that change will be necessary. But knowledge is not enough. Leaders who are effective change agents manage to make change happen--regardless of how many obstacles they face, what the economy does, what kinds of problems their people experience, and so on. They fight for positive change because they know what's at stake!
Committed change agents keep their team moving forward. If they gain momentum, they don't back off and coast. They press on and increase that momentum so they can make bigger changes.