If you’re having trouble feeling anything in the heart, then I suggest you try to notice the sensations in that area. Get to know what that part of the body feels like as you breathe. Notice as you breathe in, it feels this way, and as you breathe out, it feels that way.
Just rest your attention at the heart and become conscious of the changing sensations there. As different events unfold, this area will become more alive because of your consistent attention to it. If you repeatedly pay attention to something, then your attention will tend to go there naturally. For example, if you’ve been practicing mindfulness of breathing at the belly, then you’ll find that your awareness will tend to gravitate to your belly even as you eat your food.
In the case of the heart-sensitizing practice I’ve been describing, you’re learning how to focus on a certain part of your physiology. This is very different from trying to manufacture an experience. As you abide more and more in the region of the heart, you’ll eventually notice more of what’s going on there, whether it’s a negative contraction or an opening of sorts. From there, your heart-centred practice will continue to evolve naturally.
This reflection by Ajahn Viradhammo is from the book, The Contemplative’s Craft, p. 154.