In my own rational sense, meditation is about living in the present moment. But each person's experience of the present moment varies, and so naturally, the exact meaning of meditation is also unique. A wise man once said, "As many minds, so many paths." Just in the way that two people can watch the same movie and get two entirely different things out of it, meditation also yields subjective experiences.
Many of us aren't used to really looking within: at our thoughts, our intentions, our truer selves. And when things around us are going on full speed, it can be even more difficult to be aware of what's going on within us. So, one way to think of meditation is as an intentional simplification, a slowing down of sorts.
When we are no longer able to change a situation - we are challenged to change ourselves." In life we are often faced with unwanted circumstances -- an unachieved goal, an insult, an injury, or even worse the loss of a loved one. Often times, nothing can be done to change things on the outside, and despite knowing that rationally, it proves difficult to even accept things the way they are, let alone be at peace with them.
Meditation is about accepting that challenge to change ourselves, and transforming our habits of interpretation. By learning to understand and focus on what is real, we go beyond the apparent reality and into subtler realms of our experience, becoming more connected with what is true for us. Fortunately, that which is real is continuously manifesting itself in this present moment, and in every present moment. It's as simple as that: just by letting go of the past and the future, we remain with our awareness of reality and increase our ability to embrace that reality.