[KatesFate]

"But what if you did?" - "You have to lift it up" - I think this 'did' something to Jack.

I always felt that this statement from Desmond meant more as well. "You have to lift it up" surely referred to more than Jacks foot.

We could argue that Desmond saved Jack at the stadium. He injected "hope" into Jack, albeit AFTER the operation but he made Jack believe nonetheless - or so I would like to think.

I think Desmond and Jack's "connection" OFF-Island was probably why they chose Jack to save Desmond in this episode, while also [as D-Roc says] making the "see you in another life" goodbye more powerful.

It was more poignant due to their off island connection. I think you may be right about Des injecting hope into Jack. That scene remains one of my favorites.