And I always use the "options" argument. I don't know and she doesn't know what she will want to do when she is 20. I want her to have options. Does she want to have options?
So when she procrastinates or does poorly, she is limiting her options.
I remember being 20. I didn't have the slightest idea what to go do with myself, but I was furious at life and quite depressed, so I basically decided to trash my academic life because I no longer cared about anything.
That didn't really have any positive outcomes. Unless you consider law school a positive outcome.
I like the "options" idea better than my approach.