The heart has three states: healthy or safe, diseased, or dead.
1 A safe heart.
There are many scholars' definitions of a healthy (safe) heart. However, the most inclusive definition is a heart that is safe from the impulse of lust that goes against God's commands and His prohibitions, as well as safe from all doubts that contaminate the news (from God and His Messenger), safe from forms of slavery to other than God, safe from judging other than Allah, safe in his love for Allah by making the law of the Messenger of Allah, may God bless him and grant him peace, as a rule in fearing, hoping, and trusting in Allah, repenting to Him, humiliating oneself before Him, prioritizing His pleasure in every condition, and keep away from His wrath in various ways. This is the nature of ubudiyah (servitude) which cannot be given except to Allah.
2 Diseased heart
A diseased heart is a living heart but has disease.
This heart has two elements, namely good and evil. Sometimes one element attracts it, and sometimes another element, depending on which one is in power.
3 A dead heart
A dead heart is a heart that has no life. He died not knowing his Lord, not worshiping Him with His commands, not loving and accepting Him. A heart that is always with lust and pleasure, even if it contains the wrath and hatred of God.
When he has indulged himself with lust and all his desires, he does not care whether God is pleased or angry. This heart is in submission to other than God.
Likewise, love, fear, hope, joy, hatred, exaltation, and self-servitude. If he loves something, he loves it because of his lust. When angry, he is also angry because of lust. If he gives, he also gives out of lust. Likewise if he does not give, it is because of lust.
Lust is what dominates him. He loves lust more than the love of God. Lust becomes its leader, lust becomes its driver, stupidity becomes its driver, and negligence becomes its vehicle." (See Mawaridul Aman Muntaqa min Ighatsatul Lahafan pg. 33-37)
Guidance from Allah subhanahu wa ta'ala will distinguish these three heart traits and will clearly show their owners.