Typically, people who exercise, start eating better and becoming more productive at work. They smoke less and show more patience with colleagues and family. They use their credit cards less frequently and say they feel less stressed. Exercise is a keystone habit that triggers widespread change.

This process within our brains is a three-step loop. First, there is a cue, a trigger that tells your brain to go into automatic mode and which habit to use. Then there is the routine, which can be physical or mental or emotional. Finally, there is a reward, which helps your brain figure out if this particular loop is worth remembering for the future: THE HABIT LOOP

Grit, which they defined as the tendency to work strenuously toward challenges, maintaining effort and interest over years despite failure, adversity, and plateaus in progress.

If you believe you can change--if you make it a habit--the change becomes real.

Once people learned how to believe in something, that skill started spilling over to other parts of their lives, until they started believing they could change. Belief was the ingredient that made a reworked habit loop into a permanent behavior.