It is hard when a loved one is suffering.
Depression can be draining both to the person diagnosed with it as well as their partner. When someone is depressed, they do not feel like doing a lot or even going outside and socializing.
It may be helpful to your husband for you to remain consistent in your encouragement to him to go out with you dinner, movies, walks amongst nature, etc. The medication and the light box are both effective. If he is open to counseling you may want to encourage him to give it a try and he is willing for you to go with him as support. Staying socially and physically active is quite helpful in individuals who are depressed.
Living with a Depressed Spouse by Gay Ingram (Paperback - Oct 16, 2007)
What To Do When Someone You Love Is Depressed : A Practical, Compassionate, and Helpful Guide by Mitch Golant Ph.D. and Susan K. Golant (Paperback - Mar 15, 1998)