Sure, the practical implication is to not give yourself short-term pick-me-ups (like a cookie to help you concentrate) or to expect yourself to lose willpower when doing something difficult (a belief which would drastically limit your overall motivation).
Hmm, I wonder what evidence you have to say “there is definitely a limited amount of mental energy”? I’m not saying there isn’t, but just wondering what kinds of things that make you experience this. I have a couple competing models I’m thinking about. It seems that attention is the conserved resource in the Obama suit example, and I’m wondering if it’s also the case in the hard-thing-first scenario (the days gets more distracting after the morning with little matters compounding).
Blatantly pasting from the bit in my book I wrote about this:
There are several competing models of willpower. The oldest model says willpower is an innate character trait, and you’re either a strong-willed, disciplined person bound for success, or you’re not. If this model is correct, then you would probably know whether you have a lot of willpower or not much. If you do have a lot, then you can rely on it to carry you through the hard parts on the way to your goals. And if you don’t, then you’d better pick out a smooth path to your goal from the onset, or you’ll fall off.
A more popular model of willpower is that it’s like a muscle. The more willpower you exert, the less you’ll have that day with which to resist further temptations, but the more you’ll have in the future as your will strengthens. Were this ego depletion model true, you’d want to make sure you weren’t going to need to use too much willpower at any given time, leaving your will weak for when you’d need it most. You would avoid Ben Franklin-ing out by trying to do too much at once, and instead aim for a modest exertion of will as you pursued your goals.
A third model of willpower is that willpower works like a muscle only if you believe it does. If you think that resisting a cookie will make you slack off later, then you’re more likely to eat the cookie in hopes of saving willpower for working later, or to slack off if you’ve already done well by resisting the cookie. If you don’t believe in willpower as an exhaustible resource, then the cookie has no effect on slacking off. In this case, you don’t generate the excuses which sap willpower.
Some thinkers have suggested that willpower doesn’t exist, that all of human behavior is explainable without invoking special cognitive intervention to override our natural interests. Psychologist George Ainslie’s response to this is my favorite concept of will: “the will is a recursive process that bets the expected value of your future self-control against each of your successive temptations.” That is, will is simply the process of making personal rules for ourselves that will help us reach our goals, and how much willpower we can muster is precisely how good we are at setting up these personal rules so that the we always prefer to keep our rules than to break them. This is a learnable skill.
The last one–the Ainslie model, based on hyperbolic discounting of different mental processes bargaining about things at different timescales–is what Danny is talking about. Beeminder works well with this model. I like it because it gives you a path to becoming more effective. You just realize that the excuses and exceptions you make, the personal rules you break, are the only thing holding yourself back from trusting yourself to get things done and do what you said you would do, and that trust is basically the strength of your will.