Idk why but for some reason i step thinking i'm going to die of cardiac arrest it scares me i don't have any health or heart condition please tell i'm overthinking ??

Fear of Cardiac: Please have an evaluation by a physician. You could be missing something important. Without a medical cause, it sounds like you are experiencing anxiety related to your physical functioning. You may benefit from discussing this with a psychologist. Often relaxation training helps. Trying to get over this on your own may not work, and your anxiety might worsen.