Start with a square piece of paper
Fold the paper in half diagonally to make a triangle
Unfold it
Fold the paper in half diagonally the other way
Unfold it again
Fold the top corner down to the center
Fold the bottom corner up to the center
Fold the left side inward to form one side of the heart
Fold the right side inward to form the other side of the heart
Round the top edges by folding the two upper corners slightly inward
Flip the paper over
Adjust the folds until the heart shape looks even