To echo some of the other comments, but add some further conceptual support, Motivational Systems Theory, (Motivating Humans, Martin Ford, 1992, Sage) suggests that both Goals and Personal Agency Beliefs (PABS) are critical components for human motivation. As Martin is an educator first and psychologist second, his ideas are very relevant to us as instructional technologists.
PABs, like Bandura's concept of self-efficacy can be activated by positive encouragement from an influential "other." By encouragement, I mean specific feedback that identifies exactly what the learner did correctly, what needs to be changed, expresses a belief that the learner is, indeed, capable of such change, and identifies contextual mechanisms (for example the availability of the instructor for additional clarification) that will support their progress.(This concept of encouragement is distinctly different than "praise," as has been pointed out by the National Training Laboratory for the Behavioral Sciences.)
But a critical point Ford makes is that "personal agency beliefs only matter if there is some goal in place." Clearly you can't activate the PAB as a cognitive and affective process if there is nothing to direct it towards. Here is where the teacher can help provide this activation by setting good instructional objectives which are at some level explicitly known to the learner. After all, if you can't see where you're supposed to be going, how can you possibly feel competent and confident about getting there?
All of this presupposes that the learners are somewhat intrinsically motivated to be in the classroom at all which, as those of us who have instructed both in academic and corporate settings know, is often a dream. But I have personally found that, even those learners who enter the classroom and look at you with the expectation that you will magically pour "learning" into them, can have their level of motivation enhanced by clear objectives supported by encouraging feedback and support.
I'm not suggesting that we should try and turn ourselves into psychologists in order to help our learners achieve the objectives that we set for them. Just that we apply common-sense and caring, whilst being aware of these concepts.
Keep working to make a difference!