"Mindfulness" refers to that move where you notice your mind wandered. With mindfulness you monitor whatever goes on within the mind. "Meditation" means the whole class of ways to train attention, mindfulness among them.
My greatest failure ended up becoming the best thing that ever happened to me. About one year into my time in the brig, I started learning about mindfulness meditation and immediately noticed an increase in happiness.
Since uncertainty is the rule, when we think we know, our mindlessness is in charge. The simple act of noticing is engaging and reveals that events don't cause stress. It is the mindless view of events that leads to stress.
Grounding yourself in body sensitivity serves as a circuit breaker to take you out of your chronic "fight or flight" state. Practice becoming aware of another's experience, especially when that other is your own body.