Nature, body, mind go to death, not we. We neither go nor come. The man Vivekananda is in nature, is born and dies. But the Self we see as Vivekananda is never born and never dies. It is the eternal and unchangeable Reality.
Take up one idea. Make that one idea your life - think of it, dream of it, live on that idea. Let the brain, muscles, nerves, every part of your body, be full of that idea, and just leave every other idea alone. This is the way to success.
For a warrior, nothing is higher than a war against evil. The warrior confronted with such a war should be pleased, Arjuna, for it comes as an open gate to heaven. But if you do not participate in this battle against evil, you will incur sin, violating your dharma and your honor.