Sherry Allchin wrote a two-part blog on emotions with the main idea being simply this: We feel what we feel because we think what we think and do what we do!
She contends that emotions, then, are a by-product of what you think about your circumstances and about your God, and how you act out on those beliefs. Emotions are good, for even God has emotions. He has given us emotions to assist us in identifying circumstances and motivating us to change. She mentions the issue of chemical imbalance but urges us to consider as other imbalances as well such as the physical, social, mental and spiritual spheres as well that can get out of balance.