1.He was only 12 years old./ He was 12./ Twelve years old.
2.He felt that he was the unluckiest (person) in the world./ He felt very sad./ Unlucky.
3.He would never care how other people looked at him and he decided to learn to do things himself.
He decided to face the life himself./ He decided to solve problems himself.
4.He taught himself all the middle school subjects,learned to drive,to go rock climbing and ski.
He studied hard and tried to do everything that common people could do.
He not only taught himself all the school subjects but also learned to go rock climbing and ski.
5.You are what you think you are!/ Disabled body,healthy life./ Great difficulty,great success.
(答案不唯一)