Our hearts, according to Proverbs, are where the source of life (from God) springs forth. Out of our hearts is where our purpose flows, our momentum, our hope. Because of this, the bible says that our hearts should be guarded - "above all else" (Prov 4:23). A heart that is free, and flowing with righteousness - an "upright heart" is what God finds pleasing to God - and what leads to the most fulfilling life.
Life can sometimes bring unexpected and harsh moments to our tender hearts. Disappointment, loss, set-backs. All of these can wound our hearts, and a wounded heart needs care. Allowing God to heal our hearts is the first step.
The second thing to remember, is that a strong heart is an open heart. A heart that is open to people, filled with hope, and brimming with the goodness of God. How is your heart today? Is it downcast and downtrodden? Is it wounded? Or maybe your heart is simply offline, and unavailable for what God wants to do. Whatever it is, it's important to open your heart to what God has, to open heart to God's healing, and to believe that if your heart is open to God, and to his will, he will guide it into the most bountiful places.