Personally I have seen both. Probably more failures than successes and I feel the positive outcomes propel me more. Its like a positive reinforcement for your efforts. There is only so much one can tap into ones dwindling motivational resources. It is easy to say, 'Be your own cheerleader', but very very difficult to put in practice. That is why I somehow don't think very much of people who have always seen only an upward trajectory. They most often lack perspective. They will also be the first to crumble if and when shit goes south. People however seldom learn from successes. In my opinion it is easier and more motivating than learning the hard way.