Dictionary Meaning:
Strength of mind; great courage or fearlessness; fortitude.
Courage and resolve; strength of character.
Indomitable spirit and perseverance & passion for long-term goals.
The Concept:
"Grit in psychology is a positive, non-cognitive trait based on an individual's passion for a particular long- term goal or end state, coupled with a powerful motivation to achieve their respective objective. This perseverance of effort promotes the overcoming of obstacles or challenges that lie within a gritty individual's path to accomplishment, and serves as a driving force in achievement realized." - Wikipedia
There are plenty of scientific researches done on this topic, many authors have written books on it, self-help gurus talk about it and almost every top blog has promoted it.
I believe that Wikipedia's definition is profound enough to state the essence of this mindset.
If you have noticed, you will find that all the mindsets are woven to earn other. They are synchronized and interrelated like a woven mesh. That's the beauty of nature and collective intelligence.
I don't think there is any need to explain why grit mindset should be developed. So let's take a quick look at some of the facts related to how you can develop this magical superpower.
Resources: If you would like to put in some extra efforts I will recommend you to read this article at forbes.com which describes the theory & research in depth. I have inserted a link to the article on the reference page, type it or simply search "Grit Forbes" on Google.
To understand this concept emotionally you can watch Will Smith's movie "The Pursuit of Happiness" a very powerful movie projecting a perfect example of a man with grit.
How to develop grit mindset?
"Grit is the stubborn refusal to quit." - Jonah Lehrar "No grit, no pearl" - unknown