I struggled for years to quit smoking, then after many failed attempts I stopped without any difficulty. I've also experienced this on other things, like when I'll want to do something but I lack the discipline to do it, then eventually I'll have a surge of energy and willpower that will make it easy for me to get anything done.
What is the psychology behind this yo-yo surge of willpower?
How can I encourage my mind and body to bring on that heightened willpower?