When I'm speaking of impatience, I'm speaking more of "living in the now" than anything else. I have a real problem with this sometimes, spending too much time and energy looking towards, or worrying about, what is next rather than what is now.
Wishing time would hurry up so I could get to whatever plans I had later that day. Wishing today would just get over with so it could be tomorrow, when I might get that reply to my e-mail that I'm awaiting. Wishing the weeks would pass by faster so it would get to spring sooner.
Life is so terribly brief, we get so little time on this planet, why waste even a second of it just trying to get to the next second? This is a key aspect of mindfulness, always being in the moment. Whatever it is you're doing at any given time, be doing that. Savor it, no matter how basic (or even, perhaps, unpleasant) an act it is. There is no then, there is only now.
I have at least taken the first, important step: identifying it. I know that I lack mindfulness many times throughout my day, and I'm getting better at recognizing when I'm doing it (and correcting it.) I'm going in the right direction, I may never attain true mindfulness but I'll always keep pushing towards it in a never-ending process. A "process of becoming", to borrow a phrase from a dear friend.
And that, I think, is life. Always "becoming".