Mindfulness or meditation can be as simple as focusing on breathing in and out or watching a candle flicker or clouds pass overhead. Savoring a meal or relaxing during simple physical chores can also be mindfulness activities. It simply means focusing on the present and letting go of thoughts of past or future worries or projects.
Walking or bicycling or other physical activities can also be opportunities to let the mind wander. Creative problem solving may be a benefit when the mind is given the time to relax solutions may emerge later. Art projects or writing in a journal can also be relaxing and free the subconscious to work through problems or worries.
For more about mindfulness, and positive stress - having a sense of purpose and feeling challenged in a good way, see G3.1: Positive Stress.
For more about forming habits, improving communication skills and assertiveness training for reducing negative stress see G3.2: Neuroplasticity.
For a list of who is more at risk for experiencing negative stress and a few antioxidant foods that may help reduce negative effects of oxidative stress see G3.3: Negative Stress.