Here are some links to places that have great suggestions on how to train the brain to improve executive functions.

LumosityThis is a site that you get a free trial but then you have to pay.
From the website..."The brain needs care just like the body. New scientific research shows that we can improve the health and function of our brains with the right mental workouts. Scientifically designed brain fitness program. Lumosity is designed by some of the leading experts in neuroscience and cognitive psychology from Stanford and UCSF. Demonstrated to improve memory and attention. Lumosity was shown to improve basic cognitive functions in randomized, controlled clinical trials."