If you keep your attention in the body as much as possible, you will be anchored in the Now. You won't lose yourself in the external world, and you won't lose yourself in your mind. Thoughts and emotions, fears and desires may still be there to some extent, but they won't take you over.
Practicing the Power of Now: Essential Teachings, Meditations, and Exercises from the Power of Now (ed. New World Library, 2001) - ISBN: 9781577311959