Mindfulness practice can be compared to weightlifting or cross-training. If a world-class runner wants to improve her pace, she will not only run, but will engage in structured exercises to help support fitness and capacity, including weightlifting, yoga, and more. If you want to improve your mood or decrease your sense of self-judgment, etc., regular and structured mindfulness practice is one thing that can help.
The recommendation for regular practice is to sit or lie still, without being tense or rigid about your posture. Mindfulness practice will ask you to move your focus from one thing to another, to “scan” for inner and outer qualities, and at various times to pay attention to your thoughts and your body sensations. It is non-religious and “guided,” for the most part, which means someone will be talking to you and giving you cues about what to focus on and when.