How to get back to normal?

About 5 years ago I developed a heart condition where my heart would just start racing. I had to be shocked back into normal rhythm many time in the ER. After 3 years they finally fixed my problem with a cardiac ablation. They told me there was only a 5% chance that it would return. It took about a year but I don't worry about that anymore.

But now every time anything feels strange I worry. If i get a headache I think it's a tumor. If I have diarrhea I think it's colon cancer. If my legs hurt I think I have a blockage in them. If I get dizzy I think it's my heart. Now I know my heart is fine because when they where trying to diagnose my heart condition they ran every test on my heart they could and found nothing structurally wrong. And I never felt these things before my heart messed up.

What I want to know is how do I get back to the way I was before I was 33? When I didn't worry about these things.