Mihaly Csikszentmihalyi talks about the mental state called: Flow in his book with the same title, where we are super focused and lost in one thing. We become obsessed and work all along. There is no time or days in consideration. We get lost in a unique world of our own. We become super creative and find ways to do the unknown.

I see flow in one more aspect of life: living to the maximum now. It saves us from wandering in the past or worrying about the future.
We are in it now at this very moment.
We enjoy and live in it.
There is no clutter, anguish, or pain about anything.

Living in flow is about living in now. And it is not easy.