|This is a return review. Thanks again for yours.
I like the idea of this poem.
However, it needs some fixing.
One, sentinel is a noun, so the first line should be
If fear stands as a sentinel within you
Two, the third line starts Let them do...
Since sentinel is a noun and it is written as singular it should read Let it
Third, in the third line you use the word do, but what does it do? You could replace that word to convey your message more specifically.
I really like that first line. It catches the imagination.
The second line builds on it, but the third line is a little vague.