Taking a Loan from the Willpower Bank

This NY Times article titled Tighten Your Belt, Strengthen Your Mind is about our ability to control willpower. That applying willpower toward one task depletes your willpower for another task. For example, if you want to not drink at a party, then you would need to reserve your willpower for that task. But if you go clothes shopping ahead of time, knowing you can't spend any money, chances are you will use your willpower (and probably will have a hard time not drinking at the party).

When embarking on a new journey or task, do we allow ourselves to harness willpower for that purpose? Or do we hold all parts of our life to the same standard and wonder why we can't apply the same energy to everything?

Knowing there is a finite reserve of willpower, how would that influence your choices each day?