There is no scientific evidence to suggest that raising your left hand exercises concentration. Concentration, also known as attention, is the mental state of a person when he or she focuses on a certain thing or activity. Factors that affect concentration include life environment, innate temperament, too much stimulation, and insufficient activity of large muscles. Concentration improves with age. To exercise concentration, professional training through listening training, number faxing, finding differences in sentences and retelling audio stories can achieve satisfactory results. If you find a decline or abnormal concentration, you should go to a regular hospital rehabilitation department or psychiatric psychology department under the assessment, to determine whether there is really abnormal concentration, if there is indeed a problem in this area, you should actively look for the cause of the disease, and then carry out targeted treatment and training.