What is Herbert saying in this poem?

What Herbert is saying in this poem is that it is the
stresses of every day life that are going to bring us closer to God.  He is saying that
God knows that and that is why he does not give us "rest" alone out of all the gifts he
could have given us.

Herbert envisions God giving out gifts
and wondering how exactly to make people.  He envisions God deciding that the best way
to make us seek him is to deprive us of rest.  By saying this, he is saying that we turn
to God when we are tired, stressed, and in need.  This may not say good things about us,
but it does seem to be the truth.