Whether it's a brisk walk, a quick jog,martial arts, cardiovascular exercises, aerobics, dancing in your room, playing Wii Fit, anything like that will keep you feeling strong, happy and increase immunity of course. Obviously you don't have to exercise daily because, lets face it, we don't always have the time; but try to fit it in a little and there will surely be the major difference in yourself. You will notice that your immunity system has a certain big hand in bringing such a change