This is an excellent site.
Just playing games for 10 minutes a day - just 10 minutes - will help sharpen your brain power.
And what is more, IT IS FREE.
They have many interesting games. And the brain area they focus on are: Speed, Memory, Attention, Flexibility and Problem Solving.
So, without hesitation register yourself at Lumosity and reclaim your brain (this is Lumosity's TM).
Highly recommended!
One day you will return to this blog to thank me.
