When Anahata is balanced, you know how to give and receive love. When you feel withdrawn or lonely, critical, irritable or just plain lack empathy or compassion, your heart chakra is blocked.
Of course you should focus on balancing all of your chakras. However, because so many aspects of life correspond to this chakra, with love being so central to human consciousness I feel the heart chakra is the most important one to have balanced. Also, by virtue of its location, this chakra is located at the mid point on your energy system, it could be said Anahata is the midway point between heaven and earth. So when this chakra is balanced, it makes it easier to balance all the others.
If you feel your heart chakra is blocked, simply hug someone and say nothing. As you are hugging, focus your thoughts on your green heart chakra as it opens to give and to receive love, and a green light radiating out from your heart center, enveloping you and the person you are hugging in a wash of love energy.