Here in the Church, you should always be happy and positive.
Except in this morning's lesson (Book of Common Prayer), Jesus says,
"Those who love their life lose it, and those who hate their life in this world will keep it for eternal life. Whoever serves me must follow me, and where I am, there will my servant be also. Whoever serves me, the Father will honor."
To follow and serve Jesus takes us on the way of the cross. If we are with him, we will be in some gloriously miserable places. We will, if we are at all human, hate what we are experiencing.
That is to say, there is a kind of complaint that must be embraced, not just confessed and repressed.
Just remember that most people won't want to hear it or know what to do with it even if they do give a listen. It is God-sized. Embrace it in prayer, and give great thanks if God sends even one person to help carry the damn thing.