I sometimes it difficult being a human there is so much suffering that one has to deal with on this realm. I am a longstanding practitioner yet am still plagued by this question. How can I fully embrace my humanness so I can really serve the Universe? Thank you so much for considering this question...

This is an important question and it does concern everybody. In Zen we sit to awaken to our true mind. The Sixth Patriarch said: Zen is the name of mind, and the mind is the base of Zen. You say that you have done many years of training, yet maybe it was not that real type of zazen. It cannot be the zazen of the body bu needs to be the zazen of the mind. As the Buddha said in the first stanza of the Dhammapada:

This is how the Buddha teaches us that the mind is of no form. This mind of no form then gets happy, gets sad, gets lonely. Yet the mind is pure like a mirror, which simply reflects the outside world. Just like our mind, it can also simply reflect the world. So when we feel sad or happy, this is just the mind reacting to something which it reflected. We live our life by habits, so we think that it is us who suffers and at other times is joyful. When we sit zazen we practice to not get moved around be the scenery which we reflect. We need to sit deeply and reach the place in our mind, where joy and sorrow cannot reach.