1) I'm worried about the car. > 차가 걱정돼 2) I'm worried about falling down. > 쓰러지는게 걱정돼 3) I'm worried I'll fall down. > 내가 쓰러질까봐 걱정이야 In Korean colloquial, the word 'I(나)' tends to be omitted. (This is a very big difference from English )

you can say "신경쓰여" instead of "걱정된다/걱정하다/걱정이야" it's a little bit informal but possible. hope it helps.