to me 与 for me 的用法

在很多句子里没有很明显的界限,它们各自都有点象它们的词义.
FOR ME 为我（目的状语）
1.He did that for me.
2.What he had done for me made me very happy.
他为我做的事使我非常高兴.（有目的做出的好事）
TO ME 对我（状语,而更有方向的意味）
1.He said to me:Let's go.
2.What he had done to me made me very upset.
而翻译时：他对我做的事情使我生气.（可见有时不是有目的的）
比较难体会是有时又是没有什么区别.
例如：It is difficult for me.
It is difficult to me.
两句都翻译成：这个对我太难了.好在因为没区别就不用太费心了.