The only caveat I can offer, and it is a personal one, is my general distaste for the use of O as a declarative and exclamation points in general. I know that you are feeling something powerful; no need to bring it to my attention with a gimmick. How about this?
All the same, it is a beautiful poem.
‘O dreary life,’ we cry,
‘ O dreary life ! ‘
And still the generations of the birds
Sing through our sighing,
and the flocks and herds
Serenely live while we are keeping strife
With Heaven’s true purpose in us, as a knife
Against which we may struggle ! Ocean girds
Unslackened the dry land, savannah-swards
Unweary sweep, hills watch unworn, and rife
Meek leaves drop yeary from the forest-trees
To show, above, the unwasted stars that pass
In their old glory: O thou God of old,
Grant me some smaller grace than comes to these !
–But so much patience as a blade of grass
Grows by, contented through the heat and cold.