We are looking externally for happiness, but Buddha is saying instead to go within to find inner peace. Peace of mind is the source of all happiness. Growing inner peace in your mind is joyful, and then you can share that with others. For example, by training in meditation on patience we come to experience a cessation of our anger. Or, by training in meditation on love, we grow our love and we experience a cessation of our hatred. We experience a temporary peace of mind through these cessations. At first, only temporary, then progressively more profound, and eventually our peace of mind becomes permanent.