Mostly the oxygen supply to the Brian increases due to any physical activity. Stopping also curbs of the benefits that u do while gymming. Stopping from Per se does not cause any harm. Discuss your problem in details as to how this heavy headed was is affecting your life. Based on that or if u are facing any issues with the attention, concentration, memory, in which case you need take neuropsychological assessments. These assessments are done by registered clinical psychologist.

Endorphins are released when you exercise. These are feel good neurochemicals.