what does a closed heart affect?
Lack of compassion.
As well as a lack of compassion, a closed heart can be one that refuses love from others.
When you see someone that appears it would be desirable to know as a friend, or see someone who needs the kind of friend you know you could be, or see anyone in need, you are seeing a reality, a different world inside yourself that does not (yet) exist in the world outside your thoughts. If it is something good you see in your thoughts, your will comes to love the idea of seeing it in the real world outside your thoughts. And your will asks you to come up with things you can do to make it happen. So you find yourself thinking of ways to develop a friendship or of helping someone.
But a closed heart is afraid of the things you think of, for some reason, and so it, in a way, says “No” to all the ideas. So you end up in a stalemate, not doing any of the things, and the inside reality never happens in the real world, it stays in your thoughts unfulfilled.
How to overcome this? When you were baptized and confirmed, you were filled with the Holy Spirit, and he comes with graces, infusing the “Virtues” in your soul. You have them to make use of. Tell God, tell the Holy Spirit, that you want to make use of the virtue of Charity, Love, so that your love for this good internal image has hope of becoming real. Tell the Holy Spirit that you want to use the virtue of Fortitude, perseverance, so that you will do what needs to be done in spite of fear and a seemingly closed heart. God is inspiring us with images of good and great things about the way the outside world might be, and he has given us the Virtues to be active in the world, making the good and great things happen around us.
In my mind, this is what your question was about, and I saw an image of myself answering you with understandings I have learned from Thomas Aquinas. And against worry that I was not fully understanding what you wanted to hear I am writing anyway. Now we will see if there is a connection of you hearing and getting what you sought (or not, which may also be).