A man's heart reflects the man. Proverbs 27:19 (NIV)
The Bible uses the term "heart" to describe the bundle of desires, hopes, interests, ambitions, dreams, and affections that you have. Your heart represents the source of all your motivations -- what you love to do and what you care about most. Even today, we still use the word in this way when we say, "I love you with all my heart."
The Bible says what is in your heart is what you really are, not what others think you are, or what circumstances force you to be (Proverbs 27:19). Your heart is the real you. It determines why you say the things you do, why you feel the way you do, and why you act the way you do.
Physically, each of us has a unique heartbeat. Just as we each have unique thumbprints, eye prints, and voiceprints, our hearts beat in slightly different patterns. It's amazing that out of all the billions of people who've ever lived, no one has ever had a heartbeat exactly like yours.
In the same way, God has given each of us a unique emotional "heartbeat" that races when we think about the subjects, activities, or circumstances that interest us. We instinctively care about some things and not about others. These are clues to where you should be serving.
Another word for heart is passion. There are certain subjects that you feel deeply passionate about and others that you couldn't care less about. Some experiences turn you on and capture your attention, while others turn you off or bore you to tears. These reveal the nature of your heart; listen for inner promptings that can point to the ministry God intends for you to have.
When you were growing up you may have discovered that you were intensely interested in some subjects that no one else in your family cared about.
Where did those interests come from? They came from God!
God had a purpose in giving you these inborn interests. Your emotional heartbeat is a key to understanding your shape for service. Don't ignore your interests; consider how they might be used for God's glory. There is a reason that you love to do these things.
Listen for inner promptings that can point to the ministry God intends for you to have.