struggling mentally

hey ! i just need some advice , as i’m not feeling like myself at all and my sleep hasn’t been the greatest. this is due to my health anxiety. i am 18 , and i just feel like every day , this fear of getting cancer , is becoming such a heavy weight to carry and it take’s away the happiness i feel , as the moment i feel happy i’m like “ there’s no point being happy as i might have cancer “. as you can probably imagine , it’s an extremely depressing mindset to have and i was just wondering on the best way’s to cope with it all and to see the positive side of thing’s , like the fact that it’s rare in my age group. i’m just really done with it all and i could really use some advice on how to better my mindset for the new year and how to calm myself down when i’m experiencing symptom’s and will instantly tell myself i have cancer. if anyone could help , that’d be great :)