The worst advice anyone could possibly give you is "follow your heart". As humans, we tend to think of this as good advice. Follow your heart, you'll know what's best. In truth, you don't even know what's best for you, much less those around you, and certainly not God.
Sadly, as human beings, our hearts are filled to the brim with sin. We have sinful desires, and we're likely to act on them. And what's worse is that this tends to be stronger the less they are policed. We even have a tendency to invent new gods to support them!
Many times before, I have said the words "God is not a marshmallow". This is a strong reminder that there is a scarier side to God. His primary purpose in life is not to shower us with limitless blessings regardless of what we say or do. Discipline is an important element of His personality, as is eternal judgement, if necessary. Of course, this isn't something we like about Him. Especially not when He's got His sights set on us. "How could a loving God send anyone to Hell? How could a loving God do anything less than support me in every last endeavour? Does God not love me?" Yes! My friend, yes, God loves you, and that is precisely why He does not support you in every desire.
Children are beautiful examples of this. As adults, we can reflect on what we were like as children. You didn't want to eat your vegetables, you wanted ice cream and gummy worms. You didn't want to go to bed, you wanted to stay up all night and play. You didn't want to go to school, you wanted to spend all day sleeping, because you were up all night playing. The choices you would have made as children would have negatively affected you as adults. And yet, did we not all argue with actual adults over these things? I don't know about you, but I'm certainly not going to pretend I willingly followed my parents into the doctor's office...
As adults, we're not much better. We know what God says, we know what we want Him to say. We cling to our own religions, our idols, our sins, even as Christians we don't always put God where He should be. But He should be there. Thus, "follow your heart" is terrible advice. Follow God's commands? Absolutely advice worth taking. Following God is both wisdom in this life, and reward in the next. Your heart may be deceitful, but God isn't. Your heart may be incurable, but God is nevertheless able to cure it. Submit to Him, even when it is hard, and yes, it will be hard, but it will also be worth it.