Weakness

I always think my biggest weakness is that I always think too much, really too much. Sometime like while waiting for bus to come, looking at the car passing by I would come to think like what if my hand or leg got under the wheel of those passing by car ?  and my natural reaction would be to close my eyes. Then I would scold myself in my mind to stop thinking so much but it always happens.

Or sometimes when watching show I would imagine myself as the person feeling sad, happy or angry. Which is why most of the time when watch sad show I would always find tear dropping. Seriously why is it I like always think so much one??? Is there anyway to stop thinking-too-much-illness ??? I wonder ...