The concept of self-control as a renewable resource might seem strange, but it shouldn't. The internet is rife with jokes about how a long day can destroy any idea of productivity. We come home, lay on the couch, turn on the t.v. and just wait for sleep. A long day at work or school, even with friends, is physically and mentally draining.
There's a reason dealing with the even slightest dilemmas at the end of the day can feel daunting.
Self-control is like a muscle. As you resist temptations or delay gratification each subsequent attempt takes more work. Powering through data entry, doing homework, avoiding snacks, on and on your day goes asking for just bits of your ability to keep-it-together.
Will fatigue can be especially draining when we're trying to change or eliminate habits. What was once a constant, and likely rewarding, behavior we're now attempting to resist, daily. This requires constant mental resistance and serious fortitude. It's no wonder going cold-turkey is seen as a bad approach. Without help, all the effort to succeed rests on your shoulders.
And let's be clear for a second, will fatigue doesn't mean you lose control when you're worn out. It's a gauge of how easy resisting temptation will be for you. Once you've given in or have been rewarded for other behavior, your reserves move back up. The level of change is going to be different for each individual, it's important to watch yourself and learn what makes you tick.
A real drain for me is my sweet tooth, and every office I've ever worked in has had a candy bowl somewhere. After a long day it'd be no surprise to see me with a piece of chocolate or three, immediately looking for more once I'd finished. It's only been recently that I've looked into curbing this habit.
So, what can we do to ensure we stay charged, walls up and ready to resist? Just like our bodies our minds do much better after rest. Without the proper amount of sleep we start the day in a deficit, having to work harder to stay focused or consume more caffeine to be on our game. I've written before on the benefits of sleep (here) I encourage you to take a look.
If sleep isn't an option, try indulging a bit or distracting from temptation. This doesn't mean, eat candy if the goal is to avoid sugars, but to move to some other activity. This could be a few minutes on your phone, maybe you go for a walk, chat with a friend/coworker. Whatever it is, relax for a bit. And only a bit, we don't want to end up replacing one bad habit with another.
Finally, when you can, save your most rewarding tasks for last. It's always easier to start something we want to finish. There's a certain intrinsic goal we want to reach. But, this means these tasks are best at the end of the day. After we've had some fatigue set in an need a strong motivator to finish.
What works for me? I almost always end up distracting myself. I try and walk by any snacks with my phone out, focused on some other rewarding bit over my appetite.