While a person's particular attitude is not always scientific, one author has studied the mental outlook and personality traits of successful self-made millionaires and come up with some statistics. Tom Corley, the author of several books on wealth and finance, says that self-made wealthy people have a common personality trait. It's a positive mental outlook. His books point to research that shows a positive mental outlook allows the brain to function at a higher capacity. When negative thoughts are processed by the brain, the pre-frontal cortex is not fully engaged. This region of the brain is where executive function happens and when it isn't optimally used, the brain isn't as efficient
The limbic system and the brain stem are regions of the brain used in negative thoughts and, according to Corley, they don't foster traits like resilience, patience, and persistence in the same way that positive thoughts do. Focusing on goals and planning the steps necessary to achieve those goals are brain functions that happen in the pre-frontal cortex and a positive outlook is necessary to keep this part of the brain engaged and active.