The second realm, the second object of meditation is your "feelings". And there are feelings that have roots from the body. And there are feelings that have roots in your perceptions. Your wrong perceptions may bring a lot of painful feelings to you.
(5. generating joy)
(6. generating happiness)
So, in the realm of feelings, the Buddha proposed the fifth exercise which is that how to generate a pleasant feeling, a feeling of joy. And the sixth is generating happiness.
(7. aware of painful feeling)
(8. calming the painful feeling)
And the seventh, we already know, is to be there with the feeling of pain. Breathing in, I'm aware of the painful feeling in me. Breathing out, I embrace the painful feeling in me. And that is what a good practitioner should do. A good practitioner does not seek to run away from the pain in him or in her. A good practitioner knows how to generate the energy of mindfulness and concentration in order to recognize the pain and embrace tenderly with compassion. Why? Because doing so, she can calm down the pain. And that is the eighth exercise. It's very pragmatic. It's very practical.
I understand that one in-breath is enough to revive awareness. And if awareness revives, joy and happiness will be automatically generated because awareness can touch the wonders of life. So, the fifth and the sixth exercises are actually the effects of the first and the second exercises. And in addition, awareness can recognize what is going on inside and around us. In this sense, in chronological order, the fifth and the sixth exercises must be the third and the fourth exercises. But in the realm-wise, breathing belongs to body, and joy and happiness belong to feelings. That's why I guess that the Buddha rearranged the order of joy and happiness as the fifth and the sixth exercises. Anyway, without reviving awareness by the first and the second exercises, the rest of 14 exercises are not possible. Therefore, the first and the second exercises are the most important. In other words, everything starts from mindfulness.
The seventh and the eighth exercises are very similar to the third and the fourth exercises. Recognizing and calming are the same. Only difference is that the third and the fourth exercises take care of body and the seventh and the eighth exercises take care of feelings.