Don't regret over the past because it's over. Don't worry about the future because it is not here yet. Nothing ever does happen in the future and nothing ever has happened in the past; the only happening is the present moment. And yet everyone is so concerned about the past and future that the present moment tends to be overlooked. Yet this present moment is the only moment of reality; everything else is imagination. Now is the only time we can live. We can't live in the past, although some attempt it, and we can't live in the future. We live now or not at all. Nothing has happened in the past; it happened in the NOW. Nothing will ever happen in the future; it will happen in the NOW. So the past is just an unchangeable memory and the future will only happen in a new version of NOW. So the only time there ever 'was, is and will be' is the ever-present NOW.