There is only one sin and it is: weakness. When I was a boy, I read Milton's Paradise Lost. The only good man I had any respect for was Satan. The only saint is that person who never weakens, faces everything, and determines die game.
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.