the secret of success (the key to success) is not so much money as a strong will. a great man is one who has a strong will and an indomitable spirit. in other words, if a man does not have a strong will to win (get) the final victory, he will never succeed in his life. he is no more than a failure.

it is quite obvious that there is no difficult thing (nothing difficult) in the world. if you make up your mind to do it, you will certainly accomplish your end. that stands to reason.

"有志者事竟成"英语作文译文:

成功的要诀不是金钱而是一个坚强的意志(用not so mush... as)。一个大人物是一个具有坚强意志和不屈不挠精神的人。换句话说，如果一个人没有坚强意志去获得最后胜利的人，他终其一生永远不会成功。他只不过是(用no more than)一个失败者。

很显明的世界上并没有难事。如果你下定决心去做它，你一定会达到目的。那是显而易见的。