I also have many family members who have died from cancer including my mother, and both my grandparents both on my mother side and my father side.
The best way to get over your fear is to make changes in your life.
Start living a healthy lifestyle.
See how the people in your family were living in their lifestyle and make sure yours is a better quality of life.
The CDC recommends 150 minutes of exercise each week. This could be simply walking for half an hour five times a week.
You could also work out and do resistance training. If you have not worked out in a while or are tight on time try doing some resistance training like push-ups, pull-ups, or dips for 10 minutes, three times a week. Then work your way up to 30 minutes, three times a week.
Start eating healthy.
Eat more fruits and vegetables and eat less processed and packaged food. Also eat less sugar. Sugar feeds cancer while fruits and vegetables reduce your risk of cancer because of their antioxidants and phytochemicals.
Get 7 to 8 hours sleep a night. Try turning off all screens 30 minutes before bed.
Make time to relax and destress. This could be yoga, meditation, listening to music, whatever helps you relax in a healthy way.