Thank you for taking proactive steps to improve that ratio, drew.
In all seriousness, though, simple conditioning through positive and negative reinforcement is both an ancient and unwieldy pedagogy. All too often, you find that your rewards teach the wrong lessons, and as you point out, negative reinforcement ceases to really teach a lesson after awhile. People learn when they either want or have to, and people are most likely to struggle with something at certain critical intersections of task difficulty and personal ability. Really, though, perhaps this might be the best response:
Allan Bloom, Closing of the American Mind wrote:
"Education in our times must try to find whatever there is in students that might yearn for completion, and to reconstruct the learning that would enable them autonomously to seek that completion."
Based on what you've shown me, I recommend you read an old book: B.F. Skinner's
Beyond Freedom and Dignity. I think you would find it both enlightening and empowering as you continue to interact with the human race.