I'm not a doctor, of course, but for those who are depressed, but where it's not debilitating, or where you are not suffering from some kind of clinical depression where you need medical attention, I highly recommend that you immediately purchase the book "Wherever You Go, There You Are: Mindfulness Meditation in Everyday Life" by Dr. Jon Kabat-Zinn, and put that information into practice as soon as you can.
Thanks for the recommendation. Do you have personal experience with this book? Do you mind sharing your thoughts on the book as well as the practice of mindfulness meditation?
With regard to emotion, like I said, mindfulness isn't meant to eliminate emotions, or even eliminate negative emotions. If something makes you mad or angry, you may carry that emotion into later tasks. Mindfulness is about recognizing the anger, acknowledging it, but understanding not to project onto other things.
There's probably more to it, but I was trained in mindfulness by proxy of martial arts (that was the study) [1]. I never studied it outright and only took a Mindfulness Attention Awareness Scale survey a few times over a few years. The paper I linked might give you some ideas on what mindfulness is.
[1] https://journals.sagepub.com/doi/pdf/10.2466/22.23.PMS.116.1...