Strictly speaking, ethics are beliefs: if you have poor ethics, you have lax standards; but your morals are your behavior: if you have poor morals, you behave badly. You can have high standards but still fail to follow them: strong ethics and weak morals. “Morale” formerly had both these meanings and you will find them attached to the word in some dictionaries, but you would be wise to avoid it in either of these senses in modern writing. By far the most common current use of “morale” is to label your state of mind, particularly how contented you are with life. A person with low morals is bad, but a person with low morale may be merely depressed.