I reject the modern/new age/yoga definition of mindfulness.
"One of the most striking features of mindfulness as taught in the modern world is how far it differs from the Canon’s teachings on right mindfulness. Instead of being a function of memory, it’s depicted primarily—in some cases, purely—as a function of attention to the present moment. Instead of being purposeful, it is without agenda. Instead of making choices, it is choiceless and without preferences." - Thanissaro Bhikku from Right Mindfulness
In a very crass phrasing, mindfulness is more than being in the present moment. In fact, clinging to the present is as pointless as clinging to the past or future. As I type this sentence, I am doing so in the present. But that present is now five second gone. Thus, being "present" is an irrelevant practice because it does not accurately convey true mindfulness. Mindfulness, as taught by the Buddha, is framing ones thoughts as they arrive and weighing them.
I want candy, I think. A non-mindful mind would say that and just buy candy. A mindful mind asks why they want the candy, when was the last time they had candy, why do I need candy, what happened the last time I bought candy, what does candy do to my body when I eat it? Why do I want this video game? I could easily purchase it. When was the last time I bought a video game? How many video games recently have I finished? How many games recently have I ENJOYED? Why do I NEED this video game? I eat my lunch. Rather than eat it with empty thoughts, I notice its texture as I eat it slowly, how does it taste, how does it smell, how does my body react to it? What kind of journey did the food take to reach my mouth? How did the pig that died for me to continue living die? How does this effect other pigs? I think of that pigs suffering and sacrifice as I eat that ham sandwich.
I'm on a street corner and a hot man walks by. Being mindful, I am aware of how that makes me feel. It fills me with desire, and I'm acutely aware that it is desire and nothing else. But being that I don't know him, I let the desire go, and continue on my way.
Mindfulness is doing an act and weighing that act and being mindful of yourself, to others, and where you are. It isn't so much as being present as it is a form of mind training as you OBSERVE your mind rather than passively give into thoughts without thinking over them.
Mindfulness is important, true. But it isn't the main focal point or result of meditation, but one of many. Never mind that there are multiple forms of meditations There's nothing wrong with mindfulness, but the western obsession with it in the context of meditation for instance is becoming exceedingly intellectually dishonest.