From the Recommended Reading page, a couple of titles worth highlighting: The Mindfulness and Acceptance Workbook for Anxiety and The Mindfulness and Acceptance Workbook for Depression, a matching pair of Acceptance and Commitment Therapy (ACT) workbooks.
Instead of trying to take on and eliminate difficult thoughts and feelings, ACT encourages accepting them and getting on with what’s most important to you. Identifying what’s most important to you is a big component of the approach.
For a reading-free sample of Acceptance and Commitment Therapy, try one of the audio exercises linked here. A whole sidebar full of free ACT audio and worksheets awaits at Live Mindfully.