now that you have 
eliminated stress you can begin considering working on your fluid intelligence.
There are two ways to the G spot ---> 
NOVELTY and 
CREATIVITYNovelty, novel, new, unfamiliar, strange... that  which can make you feel insecure, excited and shakes your ground, THESE  situations are the of kind that you want.
by facing novel challenges you gain experience and new valuable neurodes. if you feel confused it is usually a good sign, it means that your brain will have to do some work to make sense of the dynamic that you´re involved in. you will have to make a creative effort to bring about a new understanding. wich implies creating a new neu-ral network to handle the situation,  the brain will have to rewire itself.                  
 + CONNECTIONS =  + VERSATITLIY = + INTELLIGENCE
You can learn a new language, or  master a random, yet useful, skill.
It´s gotta be something NEW, and something MEANINGFUL to you.
the main idea is challenging your gray matter with something unexpected, regularly.
conquering challenges is the spice of life.
But this is half of the equation.... You still need
TO USE WHAT YOU KNOW TO PRODUCE WHAT YOU DON´T
Create, Create, Create
You are a MasterMind,  you were meant to create, your brain works by association, and this is  core the principle of creativity. Unleash a creative thunderstorm which will crystalize something BRAND NEW onto reality, mix unrelated things and cook on your head something marvelous. just for the kick of it.
by creating you are using the ultimate brain training. you are stepping out of the habitual patterns of thinking.  you use all your crystalized-database arsenal  in your mind oven using the fire of your creative flame.
Write a Fictional story, 
Draw a portait, Program an applet or game, Become a mangaka, Sort out your knowlegde and ideas by blogging.
when you produce you take your technical and theoretical knowledge to another level.
Try it. you will see that  without mastery, you cannot materialize creation nor transmit the knowlege to other beings properly.
All intellectual work must be productive, otherwise is useless
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Bottomline:
Creation is the ultimate brain training.