Gratitude and finding things to be grateful for is definitely a help.
One thing I do that seems to help is visualizing good things whether it be seeing myself succeeding or accomplishing a goal, or what have you.
Also, someone once told me that your emotions, circumstances, etc do not define you. Your worth is something that never changes, whether you are an important CEO, or a homeless person, or a drug addict. Every person's worth is constant and never changes. You don't have to do anything to prove your worth because it is ALWAYS there.