When you say to yourself, 'I am going to have a pleasant visit or a pleasant journey,' you are literally sending elements and forces ahead of your body that will arrange things to make your visit or journey pleasant. When before the visit or the journey or the shopping trip you are in a bad humour, or fearful or apprehensive of something unpleasant, you are sending unseen agencies ahead of you which will make some kind of unpleasantness. Our thoughts, or in other words, our state of mind, is ever at work 'fixing up' things good or bad in advance.