The idea is as simple as it reads. But, we are all guilty of obsessing about some past decision or being anxious about a future event. Both the past and the future do not exist, now is all there is.
If the above thought is philosophical, today, I read a passage from Jiddu Krishnamurti (here) that helps me put that thought in daily life (and connect it with another).
Man lives by time. Inventing the future has been his favourite game of escape. We think that changes in ourselves can come about in time, that order in ourselves can be built up little by little, added to day by day. But time doesn’t bring order or peace, so we must stop thinking in terms of gradualness. This means that there is no tomorrow for us to be peaceful in. We have to be orderly on the instant.
It is only then [when the mind is completely still] that the mind is free because it is no longer desiring anything; it is no longer seeking; it is no longer pursuing a goal, an ideal—which are all the projections of a conditioned mind. And if you ever come to that understanding, in which there can be no self-deception, then you will find that there is a possibility of the coming into being of that extraordinary thing called creativity.
Connecting them, I would conclude: There are no failures (past), no goals (future), there is only doing and exploring (now) for the sake of it.
The bit that stuck me was how much the past and the future “colour” our choices and take our freedom away. Then, it is in the now that we can attain positive freedom.