The use of words stout and brave suggests that our hearts are

The use of words stout and brave suggests that our hearts are courageous and determined.
The lines say that even though we are brave and willing to move on, the circle of life is such that at one point, we are all going to die whether we want that or not. We can try as much as we want, but death will come for us eventually, so all we can do is live our lives to the fullest.