CC's comments are right on point. Mindfulness-based meditation is my preferred technique. Mindfulness is paying close attention, in the present moment, without judgment. One develops the practice in sitting meditation, but it can be applied to just about any activity (e.g. eating, driving, chores, etc.).

Thich Nhat Hanh has a number of good books; The Miracle of Mindfulness might be a good place to start. Another good book from Kabat-Zinn is Wherever You Go There You Are.

Notice your breathing and use that as a point of focus. If your mind wanders, just notice and accept it. Return to your breathing without chastising yourself. If an unpleasant thought or feeling comes up, do the same. Identify and acknowledge it, and just allow it to be.

Think of a pebble falling into a clear and still pool of water. Some ripples are created, but they quickly subside and the surface returns to glass. A thought or feeling may cause ripples, but just accept it and allow the pond to return to glass.