Gratitude is crucial to our own well-being and our being able to function well in personal and social/work relationships.
Dr. Richard J. Krejcir offers an excellent article titled The Discipline of Gratitude. An interesting quote from it says, "It is essential that this discipline of gratitude is pursued for the sake of contentment and for the sake of humanity."
Looking up A Disciple's Notebook to find the series of posts Thankful Praise, Thanksgiving Always, Be Thankful Always, and Joyful Thankfulness gives us an honest look at the difficulties in maintaining gratitude.
Last but not least, John Piper has a very short post on the topic, The Gravity of Gratitude, with helpful comments on overcoming ingratitude.
Reading about the lives of people who from all appearances have nothing to be grateful for, yet who have put their focus on God and His Word can be stunning work, and very helpful to us in our time of need. The one thing these victors over grief, bitterness, and other similar responses to difficulty circumstance have in common is their trust in the Word of God that leads them to a peace that allows them to make positive steps forward in life.