Why did Cole muster all of his energy in order to spit at the Spirit Bear in Chapter Eleven? What is the real meaning behind this act?

Cole believed that in spitting at the bear, he would have the last word. In other words, he believed that the act of spitting ffording him a source of control.

When not one more drop of moisture would form, Cole painfully lifted his head. He sucked in the deepest breath he dared. He was spitting at more than the Spirit Bear. He was spitting at his life. The world would take him to the grave with a slimy goober on its face. Cole Matthews would still have the last word.