Blaise Pascal, Pensées 
Let each one examine his thoughts, and he will find them all occupied with the past and the future. We scarcely ever think of the present; and if we think of it, it is only to take light from it to arrange the future. The present is never our end. The past and the present are our means; the future alone is our end. So we never live, but we hope to live; and, as we are always preparing to be happy, it is inevitable we should never be so.