When you have been through so much in life, it is difficult as you age because you remember so much. I loved the simplicity of the poem as a whole. One thing I noticed that is a bit "hidden" is the fact you compared human life to trees or earth life in general, I thought that was a perfect simile. As humans we have to be one with nature because nature lets us live, and it seems that nature lets you live as well.
You are feeling your age because your bones are hurting more and more as you age. Sap trickles as does age. Leaves fall and eventually begin anew. When leaves fall tress weep so I like how you are comparing yourself to a tree here. The more leaves you drop the more you weep.
51 years life has come full circle. Just a beautiful and intelligent write. Also nominated