How do I order people into danger for a cause I have to believe in?

You may have to send people into harm's way, and stake their lives on a purpose you have to believe is worth it. There is almost no heavier thing a person can be asked to do. That you wrestle with it, rather than growing numb to it, is exactly what should be true of anyone holding that authority. The doubt you feel is not a flaw to suppress; it is a safeguard. A leader who never questions whether the cost is worth it becomes careless with lives. Your task is not to erase the doubt but to do the hard work behind it: to make sure the purpose really is worth what you are asking, and to refuse to spend people on anything less. The weight is what keeps you honest. Carry it by never letting the people become abstract. Know their names, their faces, what they are risking. When you order a risk, let it cost you something to give that order. That personal cost is not weakness; it is the thing that will keep you from ever asking for a sacrifice you have not first weighed with everything you have.