The concept of a resource can be defined within ordinary decision theory: something is a resource iff it can be used towards multiple goals and spending it on one goal makes the resource unavailable for spending on a different goal. In other words, it is a resource iff spending it has a nontrivial opportunity cost. Immediately we have two implications: whether or not something is a resource to you depends on your ultimate goal and (2) diving by resources spent is useful only for intermediate goals: it never makes sense to care how efficiently an agent uses its resources to achieve its ultimate goal or to satisfy its entire system of terminal values.