I had observe one of the cause of discouraged believer is unfaithfulness. Yes when a believer did Mistake or Sin on that time he or she quit/ lose their Spiritual Excitement. But God told me that Faith will make You Faithful.So don't worry if you did mistake rather keep doing the works of faith.
But Pastor what are the works of faith? I tell you - Praise, Worship, Thanksgiving, Prayer, Assembly and Giving are the works of Faith.
Keep doing these faith works will one day make you faithful. And you will see the open heaven with a voice come my faithful servant.