Marathon as Metaphor

On my mind during National Poetry Month--how to keep my spirits up so writing a poem a day for 30 days, using a variety of forms, continues to be an energizing challenge. The form below is a combination of Decastich (10-line poem) and Tritina (repetition of first three lines' end words in remaining end words, and all three in the last line, in order, as indicated):

It's true of all marathons' nature
that our faith dims when only half-way,
our minds and our souls fully stretched to a goal
whether treasure of mind or a physical goal,
there is always a wall in our nature
where our limits are tested half-way:
where vision can falter, cast doubts when half-way,
and if learning a form makes us question the goal--
then the only relief is to trust talent's nature,
watch nature soar past when half-way to our goal.