Mantra of positive thinking in Hinduism is dedicated to Shiva. The mantra helps in overcoming all kinds and forms of negativity in life. Here is the mantra for positive thinking.
ॐ ओंकारेश्वराया नागेश्वराया नमो नमः
Om omkareshwaraya nageshwaraya namo namah
Om omkareshwaraya nageshwaraya namo namah
The mantra should be chanted daily 108 times in the morning just before sunrise. Person chanting the mantra should wear white color clothes and sit facing north or northeast.
The person wishing for positive thinking should avoid negativities like newspaper, unwanted news, bad friends etc.
The person should plant trees and take care of them.
The person should plant Tulsi plant and other herbs and take care of them.
It is also highly meritorious to feed animals too.