I've been re-reading Alan Millar's "Reasons for Action and Instrumental Rationality," and in the chapter he distinguishes between motivating and normative reasons.
For the sake of discussion, let me outline the definitions of each kind of reason. I will use Millar's definitions (p. 114 of Reason and Nature, edited by Bermudez and Millar).
Motivating reason - reasons which move an agent to act and are therefore reasons by reference to which the action can be explained.
Normative reason - reasons which provide the agent who has them with a justification for the action in question.
Is there such a clear distinction between motivating and normative reasons for action? Anyone who holds the view that the two aren't clearly distinguishable is likely undertaking an instrumental or calculative approach to practical reasoning. What we ought to do should be informed by what we want to do. For a comparison, try Michael Smith's work, especially his classic paper "The Humean Theory of Motivation" (Mind, 1987).
Like Smith, I'd like to try to argue that the two cannot be easily distinguished. Motivating reasons just are normative reasons. All of your practical reasoning must be means-end reasoning because thinking about what to do, with only beliefs and desires, will be instrumental (means-end) thinking and you have to think about what to do using only beliefs and desires. Some have called this the gears-of-the-mind argument.
If a reason moves one to act, then that reason is normative for the agent. For example, Smith goes to the grocery store because he wants eggs. The grocery store usually carries eggs. So Smith's is justified to go to the grocery store for eggs. His justification for thinking the grocery store carries eggs moves him to act, that is for him to go the grocery store. The motivating reason is the normative reason.
In the background, there is an argument that shows a motivating reason for action consists of a desire and the belief that the action would bring about the satisfaction of that desire. Motivating reasons are teleological explanations. They tell you what an action is for; they are reasons that explain actions. What an action is for is a goal. Having a motivating reason is, among other things, having a goal. Learning that the world is not as the content of your goal specifies is not enough for giving up that goal, but rather puts pressure on you to change the world. Having a goal is being in a state with which the world must fit. Being in a state with which the world must fit is desiring. Having a motivating reason is, among other things, having a desire. The other things required for having a motivating reason are means-end beliefs linking the desire to the action it's a reason for.
I would never contend that this is always the way it is. Sometimes motivating reasons are not normative. For example, my desire for an ice cream may move me to go in any number of directions without being able to fulfill my desire. In fact, one possible criticism of Smith's argument for motivating reasons of action has to be that actions don't bottom-out in a desire. For example, suppose a driver asks herself, "why are you putting the key in the ignition?" "To start the engine." The action doesn't bottom out in a desire. You explain one action (putting the key in the ignition) by placing it as a part of another action (starting the engine). This naive rationalisation of one's actions is in contrast with the more sophisticated rationalisation given in Smith's analysis (i.e., I want to start the engine). So, when you think you've got a reason for action that seems to bottom out in a desire, what you've really got is a naive ratioanalisation in which motivating reasons don't figure at all.