For depression and anxiety there are some techniques you can do on your own to alleviate your mood. It works for many people, though not for some. It occurs to me that if you end up having to rely on yourself in a survival situation, it may be useful to have these techniques, some of which are described in

The Mindful Way Through Depression: Freeing Yourself from Chronic Unhappiness by Mark Williams, John Teasdale, Zindel Segal, Jon Kabat-Zinn.

There are some internet resources connected with this book, and I think Kabat-Zinn (the fourth author) more stuff on mindfulness. With this sort of stuff, your mileage may vary.