Hi Paul,
great lyrics, made even better by being a grandfather.
The only line that doesn't work for me is the final breath. Up to then the what, where, who etc was left to my imagination. That line sort of pulled me up with "oh, I'm dying", broke up the magic for me. I like the "Life is fleeting" start as it could be about growing up into adulthood. The setting sun line gives us a choice on how we interpret the line, setting sun on childhood or setting sun on life.
Feel free to ignore me if you disagree, looking for to hearing the finished song.
Keith