Positive thought; My favorite is 'Well life couldn't get any worse so it has to get better right?'
Success Stories; I think reading other people's sucsess stories can be really usful, you can pick up tips to try over come depression.
Good Friends; I think it's really importent you have someone you trust to speak too because keeping bad feelings too your self is bad for the soul.
Or if you don't have someone to speak too at least keep a diary, to let out the bad feelings. (imo)
Mood; try to be as up beat as possible to avoid thinking of all the bad stuff.