I used to be petrified of needles. My pediatrician would have me drugged up before I came to the office when I was younger, so I wouldn't ~accidentally~ kick anyone where it hurts
I overcame that fear by donating blood whenever I can.
The two fears that I still have are being caught in a burning house and the fear of swimming in deep water. I shouldn't have let myself be so fascinated by sharks when I was younger. At least dinosaurs have been extinct for millions of years. I want to go scuba diving someday. Not just on any scuba diving trip though, I want to see the hammerhead migration off the Australian coast. I still don't know how I'm going to get over the fear of being trapped in a burning building though. Maybe volunteer as a firefighter?
The best way to overcome a fear is to face it head on imo.