Here researchers asked the question - is it the same brain process remembering a cue for action ("When you're at the supermarket...") as the action itself ("don't forget to pick up some bread")? In another setting, this may be "When the teacher asks for homework, don't forget to turn it in..."
Well, at least from the fMRI perspective, remembering the cue looks more or less like remembering the task.
It turns out both require the prefrontal cortex. Uh-oh, you say, isn't that the same place that takes a long time to mature in tweens and teens? Yep, that's right - the prefrontal cortex doesn't "blue-in" until your 20's, so don't give up.
Remembering What We're Supposed to Do & fMRI
Eide Neurolearning Blog: Your Brain with Time-Teen Brain