Why does one worry so much about death?

everyday i worry about someone in my family dieing, friends family, anyone thats close to me. Im always worrying about something and its getting to me. Im not happy at all and have no get uo and go for anything. Im already on meds and they have been changed and dosage increased so i dont know what else to do. Im just an unhappy person i guessbut how do i change ...ME?