Depression will only be 'life long' if you allow it to be. By being a little more positive and by working with your Doctor and, yes, a therapist/counsellor, you can fight against it and win the fight in the end. It may be a struggle, but the alternative is exactly what you predict - Depression for life! Yoga and similar activities will help you to take your mind off things. Meditation is another healthy option. But counselling, medication and self-determination/will are the best ways to free yourself from this illness.