Hi. I m 29m 168 cm 140 lbs, I feel pain in the middle of my chest but my all cardiac related tests are normal, I m worried about heart attack... how can I ged rid of that worry?

Costochondritis. In the middle of your chest is the bone that protects your heart and where your ribs attach. The rib attachment is a joint with a lining which like knee joint can get inflamed and when this happens the rib joints hurt when you breath and press on them. Wear good bra so breasts don't pull on your chest and exercise bra when exercising Deep breath/press over joints = pain. Condition is not harmful.