Did you ever hear a trapeze artist saying 'Now'. no, but when they are in action, now is the most important time. It's now or never. The most important person is the person who left the trapeze to be caught by the other artist.
We seldom experience regret for anything that we have done. It is generally what we haven't done (missed opportunity) that torments us. So let's 'live' in the present moment wisely and earnestly.