What does it mean to live in the moment?

It means not to lament about the things that have happened to us in the past, and not to stress out and worry about the things that may happen in the future.

Just be grateful about what you have now and don’t worry about the past or future.

Typing text into this little box (though by the time you read this, it will no longer be true).

To me it means being totally focused and mindful of your precisely current state—thoughts, feelings, senses—with no awareness of the past or future. It’s a key concept in acting and very difficult to achieve in real life. The modern expression for it, which I’ve never much liked, is “Smelling the roses or coffee.”

To hope something bad doesn’t happen again or at least right away.

I think it means that there is a time and place for planning for the future and remembering the past, but that we should fully engage ourselves in whatever we are involved in at a given moment (which could be remembering the past or imagining the future). Sort of like what @Austinlad said up to the second hyphen.

For me, it’s feeling as though you’re sucking each moment dry of its potential for enjoyment.

Amplifying and making the most of what you’re finding pleasurable or positive. This morning before leaving, I just stood and looked into my bf’s eyes in the daylight to savor their color, twinkle and the ease his face as he looked back at me. In my mind, that became the very best thing I could imagine at the moment it was happening and I drove away feeling very light and loved. That kind of thing.

To be fully focused in the present activity.
Not holding old anger about your childhood stuff and let go of blaming parents.
To appreciate the opportunity to choose your power in the manner of your liking.
To listen to your instincts, allowing what comes next.
Honoring yourself.