I used precess of elimination. U cannot improve the bone density by working out. You can improve your cardiorespiratory fitness by doing cardio, e.g. cycling, swimming, running etc. You can improve muscular strength by working out, e.g. push up, sit ups, etc. you can also become more.flexible by expanding ur muscles and tissues.
True the flu vaccine gives you a little sickness when you get the flu shot so your body can recognize it when do get it so it knows the sickness and it fights it of so you don’t get the flu