Longfellow in his poem Christmas Bells is laying out the challenge he is facing. In the process of writing, he is setting a goal that he sees he needs to strive for; setting out a path of faith that he needs to travel in his heart. Did writing the poem resolve all his struggles. I doubt it. Broken discouraged hearts are not so simply fixed. But knowing the path we should travel, remembering the promise we should cling to in the struggles we feel gives us "a way forward". We no longer have to linger where we are, bewildered in doubt and confusion. We once again have a goal we can focus on moving our emotions and faith toward.
One last thought. I've heard it said by a friend who has spent years studying & portraying Abraham Lincoln that when someone asked President Lincoln if he thought God was "on our side", meaning on the side of the Union cause, Lincoln replied something like this: It's not 'is God on our side', but are we on God's side that is important. Christmas challenges us to that goal. It's not "will God help me to do what I want" in life, but it's God calling us to accept His goals and hope. He wishes to redeem us from our sin, but we must accept His terms -- that Jesus Christ is the only way of forgiveness. Christmas, the celebration of Jesus' birth, is not about "having a good time and getting what I want"; it's about remembering that God offers what I really need at great cost to Himself. In all the distractions of life, the struggles of life, the conflicts of life, do not walk by the greatest gift ever offered: peace with God through His Son Jesus. When we accept God's gift of forgiveness through Jesus, we then have the anchor we need to navigate our way through the struggles and conflicts and loss of life to our Heavenly Home across the Jordan. "Merry Christmas" becomes a reminder that Our Heavenly Father "is not dead, nor doth He sleep, the wrong shall fail, the right prevail, with peace on earth, goodwill to men".