Something new I'm learning

Self control is like a muscle.  You can't just keep using it forever.  It gets fatigued, and needs to rest and recover.

Self control is applied in 3 basic circumstances:

• To do things we know we should (chores, disciplines, etc.)
• To avoid things we know we should avoid (vices, unhealthy choices, etc.)
• To manage negative emotions (anger, depression, etc.)

The third of these will almost always trump the other two.  Someone who uses food to manage their emotional responses will not be able to exercise their will power to stay away from food when an emotional situation arises that they aren't otherwise equipped to deal with, no matter how well they may understand that it is best for them. 

I find this very helpful to understand.