Use only positive and hopeful language for a 24-hour period. Then go back to being ‘realistic’ the next day. Repeat this over a week and you find that what you considered realistic a week ago now seems pessimistic. In golfing terms, discover that ‘the rough is only mental’. Your new understanding of what is realistic moves up to a higher, permanently positive level.
Taken from Tom Butler-Bowdon, 50 Self-Help Classics