For this reason, they must believe in the cause for which they are fighting.

Belief in the mission ties in with the fourth Law of Combat: Decentralized Command (chapter 8). The leader must explain not just what to do, but why. It is the responsibility of the subordinate leader to reach out and ask if they do not understand. Only when leaders at all levels understand and believe in the mission can they pass that understanding and belief to their teams so that they can persevere through challenges, execute and win.

Believe, obey, fight.

You must believe in what you're doing, that what you're doing is the proper thing, the right thing. And you must have faith that things will end up as they should, which doesn't mean as you want them to, but things will work out as they should.

I belive that people should fight for what they believe and only what they believe.

You have got to have something in which to believe. You have got to have leaders, organization, friendships, and contacts that help you to believe that, and help you to put out your best.

In order to convince and inspire others to follow and accomplish a mission, a leader must be a true believer in the mission. Even when others doubt and question the amount of risk, asking, “Is it worth it?” the leader must believe in the greater cause. If a leader does not believe, he or she will not take the risks required to overcome the inevitable challenges necessary to win. And they will not be able to convince

Heretics must believe. More than anyone else in an organization, it's the person who's challenging the status quo, the one who is daring to be great, who is truly present and not just punching a clock who must have confidence in her beliefs.
Can you imagine Steve Jobs showing up for the paycheck? It's nice to get paid. It's essential to believe.

As a military professional, I knew that the most important element is trust- the vision had to be built on trust. The very basis for why soldiers fight the way they do is the trust they have in their teammates, their fellow soldiers. It's usually less dramatic off the battlefield but still equally important. Without trust in each other and trust in the institution, you will not be able to realize your vision.

Once I analyzed the mission and understood for myself that critical piece of information, I could then believe in the mission. If I didn’t believe in it, there was no way I could possibly convince the SEALs in my task unit to believe in it. If I expressed doubts or openly questioned the wisdom of this plan in front of the troops, their derision toward the mission would increase exponentially. They would never believe in it. As a result, they would never commit to it, and it would fail. But once I understood and believed, I then passed that understanding and belief on, clearly and succinctly, to my troops so that they believed in it themselves. When they understood why, they would commit to the mission, persevere through the inevitable challenges in store, and accomplish the task set before us.

If you believe very strongly in something, stand up and fight for it.

I cannot believe in anything else. A man needs heroes. He needs to believe in strength, nobility and courage. Otherwise we become sheep to be herded to the slaughterhouse of death. I believe this. I am a soldier. I try to fight for the right cause. Sometimes it is hard to know.

Know why you’re in the fight to stay in the fight!

It shall always be only a fraction of the people who stand out as truly active fighters, and more is expected from them than from the millions of their fellow countrymen. For them, the mere pledge of "I believe" is not enough, but rather the oath: "I fight!"