More experience will stop your nervousness
True that some people maybe more nervous than others
But all nervous can be treated with experience.
No nervousness just stay the same.
Get someone to bring you to a parking spot
Go there when its not many cars like early morning weekend
Practice there

About your nervousness, you can reduce it by making tolerance with your body. Exercise more. Make your heart pumping.
That itself will help your body to develop resistance against feeling like shock, anxiety and nervousness. Within 1-2 weeks of like 30 minutes jogging everyday, you'll notice the difference in your nervousness as in no more making your heart rate too fast or blood pressuree shooting high