The same philosophy regarding power of thought was even narrated by
Lord Buddha, who said
'We are what we think. All that we are arises with our thoughts. With our thoughts, we make the world"
The effect of thoughts on personality was also explained by 'Swami Vivekanand' in his own words.
In the animation see an example.
Lets imagine that a Cat comes in front of a Super Mirror (which shows your personality and not the physical appearance). If her thoughts are just, she will look like a Cat, otherwise she may look like a Rat or a Lion, depending upon her thoughts.