The world says "Follow your heart" because it sounds romantic, but the problem with following your heart is that it usually means chasing after whatever feels right at the moment and throwing caution to the wind regardless of what good logic or counsel are saying.
The Bible says in Proverbs 28:26 - "He who trusts in his own heart is a fool, but he who walks wisely will be delivered". We forget that feelings and emotions are shallow and unreliable. They can fluctuate depending upon our circumstances. You hear of people loosing their life savings following a whim on a horse race, or leaving their lifelong mate in order to chase after an attractive coworker who's been married twice already. What feels right in the height of emotion often feels like a bitter mistake a few years later. Unless our hearts are genuinely changed by God, we will continue to choose wrong things. Just as our heart can direct us toward hatred, lust, and violence, it can also be directed by love, truth, and kindness. As we walk with God, He will put dreams in our heart that He wants to fulfill in our life. He will also put skills and abilities in our heart that He wants to develop for His glory. As we put God first, He will fulfill the good desires of our heart. Psalm 37:4 - "Delight yourself in the Lord; and He will give you the desires of your heart". The only time we can fully lead our heart is when we know our heart is fixed on serving and pleasing God. The Bible instructs us to lead our heart by taking full responsibility for its condition and direction. How do we lead our heart? By constantly being aware of where it is. You can tell where your heart is by looking at where your time has gone in the past month, where your money has gone, and what you keep talking about. The Bible says, " Where your treasure is, there will your heart be also." When something unhealthy tempts us, it is our responsibility to guard our heart.
Proverbs 4:23 says, "Above all else, guard your heart, for it is the wellspring of life". Your heart is the most important part of who you are. It is the center of your being, where the "real you" resides. I encourage you to identify where your heart needs to be and then choose to lead your heart in that direction.