I saw a scene from Dodgeball a few days ago. It was the scene where Ben Stiller's character was pretending to read a dictionary, and when he got called out he said, "You caught me. I like to break a mental sweat too." This line perfectly sums up something about the brain that we have begun to better understand over the last decade or so.
As an undergrad I briefly worked in a psychology lab helping to conduct a study for Dr. Miron Zuckerman and his graduate student Jordan Silberman. The gist, of the research is described in Jordan's TED talk here https://www.youtube.com/watch?v=HQ2j-p0wBLc , but I will try to some it up as well as I can.
First, let's think about breaking a sweat. When you do push-ups at the gym, the first one is probably pretty easy, but when you are finishing your set, you can barely lift yourself up off the ground. Your muscles are designed to perform a specific function, but they only have a limited capacity to perform that function. An economist might say that an individual has limited push-up resources. Even great athletes taper (do easier work-outs) before important events because they have limited athletic resources.
Now back to breaking a mental sweat. We can think about the brain like a collection of muscles; each designed for a specific function, and each with limited resources to conduct their function. Much the way push-ups get more and more difficult, psychologists have observed that when an individual is asked to do a self-control task, they get progressively worse until they fail. When you think about this, think about a time when your patience was being tested all day, so you came home and had a big bowl of ice cream even though you knew you shouldn't. You exercised your self-control until your resources became totally depleted. If we carry out the analogy to its logical conclusion, we should also be able to carefully exercise our self-control in order to increase our capacity. Much the same way regular exercise increases your exercise capacity over time. Indeed, it has been observed that when a person is asked to adhere to a simple self-control regimen (i.e. keeping a spending journal), it increases their capacity for self-control in other areas of their life (i.e. more likely to work out/study).
The TED talk above and the project I briefly worked on as an undergrad start with that premise, and carry the analogy further. Even though the instances in daily life when we have to lift dumb bells are exceedingly rare, we still do curls at the gym when we want stronger arms, because we know that we can increase the capacity of our biceps to flex our elbow joints. If that is true for our biceps, shouldn't we be able to design an analogous exercise for self-control? As we've learned more about the neurophysiology, we've learned a bit about the physiology of self-control. We now expect an EEG to show coherence between the dorsal lateral prefrontal cortex and the ventral medial prefrontal cortex during self-control activity. Given this, we can design a brain computer interface that will allow a user to lift a digital bar by making their brain use its self-control pathway. Similar to any other exercise, this gets harder and harder for an individual during a single workout, but capacity for self-control increases with repeated exercise. And this translates to functional improvements (i.e. food choices). Essentially, we are able to design an exercise for your self-control muscle.
Now... we do not need brain computer interfaces to get good at self-control, but the premise is important for self-improvement and making intentional decisions. My dad has the habit of forwarding me a whole bunch of click-bait articles with titles like "How to succeed as your own boss - Avoid the six mistakes" or "The one habit that can make the most positive impact on your life" (actual titles), and I have the habit of clicking on them. The latter, said something that really struck me. It said that when people focus on changing a single behavior at a time, the likelihood of retaining the new behavior for a year or more is 80%, but when they try 2 or more behaviors at once, the likelihood plummets to roughly 20%. What I take from this, is not that we can only change one behavior at a time, but rather that we need to be intentional about how we spend our limited mental resources; and just as an athlete is intentional about recovery (replenishing resources for the next workout), we can all be intentional about how we recover from mental exercise.
Right now, I am working on a hefty list of goals for 2016, not the least of which are writing my dissertation, creating an agenda for SA Science Inc., and reaching a handful of fitness milestones. Working towards multiple goals is taxing on my limited self-control resources, so I am deliberate about recovery, I allow myself to go for a walk in the greenbelt with my dogs for as long as they want everyday, I put away all my work away while I'm cooking and eating dinner, and I allow myself to eat out for lunch often, because it is one less thing that I have to plan and I enjoy it. By deliberately incorporating activities into our day that replenish our mental resources, we can avoid depleting those resources and compromising our goals. So we should all remember that we only have limited self-control and be deliberate, because it is really easy to come home from the gym and say "I earned that cake."