My own experiences are not so different from the examples you provide. Lost a full scholarship at a great school, changed majors few times. So at one point the motivation came,I went from a community college to Research I, but the work ethic is still lagging. I am in a Ph.D. program right now and still struggling with giving my best. For some reason just thought I can make the life easier for my ds.
I like ABQMom's suggestion to have a conversation about self-expectations.