Good posture and deep breathing will calm the body, emotions and mind.
To be mindful is to be careful and vigilant with the mind. To remain aware and present. The enemies of mindfulness are distraction and apathy. All the time that you are watching your thoughts and emotions you are mindful. Mindfulness is a good habit to adopt and is a process of refinement that will happen as long as you remain vigilant.
With calm and mindfulness you will naturally create inner stillness, this will bring you insight from the deeper part of yourself. Insight brings wisdom and an inner knowing from a far greater perspective than your normal thinking mind is able to perceive or define.
Meditation is simple. Good posture and deep breathing induce a state of calm, this enables mindfulness, when sustained, this produces insight bringing wisdom.
And done regularly, this is life changing.