I do Yoga , just sit for 10 minutes on floor and concentrat on breath and say OM while breath out and take long breath ;I do this for ten minutes .I could say this is very helpful to keep calm all the day. its really effective exercise for brain.

@Sepideh, no exercice will keep away Alzheimer if you are condemned to get it someday. It is an urban legend that especially language teacher like tell to their students. The reality is that clever people (and we sure all are here on Italki) will be able to develop some cognitives strategies to palliate to the first symptoms of cognitive loss in great age. So Alzheimer or an another kind of cognitive decline will be diagnosed clinically about two years later statistically. But the onset of the impairment started before.

Sad to say, there are highly intelligent people who played chess like big masters, achieved great things in their life whose brain and whose personality just disintegrated and came to pieces at the end of their life.