Leo Babuta in his Zen Habits blog a couple of years ago wrote a beautiful-brief essay on what he called the "Stateless Mindset". Technical background: in computer science state is the internal configuration of a system — all the information stored in it that can influence its future. Statelessness means that when new inputs arrive they are treated independently of the past.
No memory. No grudges. No clinging. Let all it go.
Babuta riffs on the theme and concludes with a lovely-mindful description of what living like that would be like:
Just this task. Just this person. Just this action. Just this moment.
There would be nothing else, just this. It would be your entire universe. It would fill you up completely.
Then it would be gone.
And the next moment would be all there was. Then that would die too.
This is stateless.
Try letting go of all previous moments, right now. Try making the present moment all there is. When you feel a previous request or idea pulling at your attention, let it go.
This is the stateless practice. You'll fail. Let that go too.
Start anew, with all the possibilities of emptiness.