Start motivated, Get worn down.
Environmental engineers tend to be the idealist, almost 50% female subgroup of the engineering discipline. We get students who want to change the world, help improve access to water and really want their work to be meaningful. Somewhere between the 4 semesters of calculus, 2 semesters of chemistry, 2 semesters of physics and one semester of biology though, you end up with a group who, sure, started because those were there motivations but really they just want a job.. And thats before the environmental engineering classes have even started.
My undergraduate institution tried and I give them credit for that. But the engineering curriculum is intrinsically designed to beat a lot of your interest in problem solving out of you before you even get started. We traditionally have undergrads front load their studies so they get the general elements out of the way. I really don't think this makes sense.
Freshman in college are some of the most idealistic people in the world. They want to be the change and they do it whole heatedly. Seniors on the other hand, have seen things, and are basically worn down by the time they get out, if they get out. I think the drive that freshman have comes from the excitement of getting to choose what you learn. For the first time! You want to help drill wells to bring water to remote populations? You're finally in the space where you can learn how to do that!
I think engineers strive in project motivated environments. That's why we became engineers. Too many of my courses were designed to teach fundamentals with little context and I'm beginning to see the value in designing a course where, yes you will need to learn how to treat water, but maybe because you have chosen a community or an issue that appeals to you.
I'm not sure I can get rid of grades but I can get rid of the idea of rigorous testing to prove a point. In today's world, engineers need to know how to find, apply and understand when equations are valuable. They don't really need to memorize the equations themselves because there is simply and I hope truly no environment in the real world where they would find themselves designing a plant or a project all on their own. I appreciate that extrinsic motivators don't work, because honestly you can cheat, and the consequences can be disastrous.
Most of us come to college with some intrinsic motivation and I think its our job as educators to make sure we foster it rather than go out of our way to squash it.