The way to "hear" God is to wait quietly, patiently and expectantly. Gods voice is not a loud, deep, thunderous, lightning striking voice.
Sometimes, Gods voice is visual.
The way to "see" hearts is very similar...quietly, patiently and expectantly (just not on your time line) The key is to not look for them at all.
Let it happen because when you do, it feels like a gift.
Like when you are struggling to hike up a hill (or struggling to get up a hill in life) and you find the best one ever and you hold on to it tightly. It provides strength when you feel like you do not have it
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The joy of finding a rock shaped like a heart is a reminder that God is always right there...no matter where you are.
Sometimes, you need to leave the hearts right where you see them, as signs for others that may follow.
Leave them there for others to find and let them feel the happiness of a rock shaped like a heart.
There are treasures everywhere, not only in the shape of a heart. 
"I will look to see what He will say to me..." Hab 2:1 (NIV)