Reading Over Time
This 32 page booklet has stories, questions, and food for thought... If your class enjoys reading and more self-directed activities, it will keep them engaged. Consider having them read portions on certain days, and taking the time to discuss the questions/activities together. Please view it first and only print the sections designed for student use.
This article from Forbes outlines 5 proven methods for building and sustaining Self-Discipline.
The Marshmallow Experiment
This article from the New Yorker analyzes an experiment connecting self-control to academic performance. On the lengthy side, consider going through it first and selecting portions, or have students read the whole thing. It is highy recommended you read it aloud as a class and discuss over several days as it is a more advanced piece.
Consider performing this experiment with your class- use candy and tell the students they can have one now, or two tomorrow if they wait, and see what happens :).
Role Playing Self-Discipline
Offer groups these mini scripts to act out opportunities for self-control and self discipline.