Brian Tracy has been around for quite some time. He has help consult with Fortune 500 companies for decades, has written over 45 books, is the author of the best selling audio program, The Psychology of Achievement (one of my favorites), speaks 4 languages, and has traveled and worked in over 80 countries.
He is big on writing down goals, affirmations, and visualizations. I've only heard him speak at an event once but I've listened to his audio tapes dozens of times. Although his speaking style isn't very intense, he is very articulate. You can visit his website at www.briantracy.com. He also has a blog that you can find on his site as well.