The best farewell song

[marionette]

Hello~

I really need your help and opinion. Here's the thing:

My friend is going far away for a long time. So me and some other friends are going to make her a present. To her card we're going to write a message/poem that should give her courage on her journey. And my friend loves Ayu.

Sooo, I decided that I should use Ayumi's lyrics.
The problem is, I don't know which song has the best "goodbye/be strong" lyrics. It doesn't have to be a whole song, it can be just a part of the lyrics.

So go ahead and tell me what song lyrics would you use, if your friend was leaving?

I was thinking that winding road might be a good one.

I apologize my bad english. It's not my native language.