Spiritual guru Eckhart Tolle's bestselling book "The Power of Now," billed as a guide to spiritual enlightenment, encourages focusing on the present rather than fretting about the past or future. Tolle posits that being in control of the direction of one's life is an illusion, and one that often leads to anxiety and disappointment. Only through the acceptance of the present can we begin to overcome those negative feelings and enjoy wherever life has taken us, as if it had been our preferred path all along.