The real way to motivate someone to learn a thing is to give them a project or something they actually want to achieve instead of trying to absorb some drivel without a reason why. That's where self learning shines. You give a great example there. A notable one of mine would be learning vector math and quaternions through trying to make games years ago, but the list is endless and not limited to math or physics.

Most teachers and professors just parrot their subject material year after year after year without EVER giving a reason what any of that is used for or where should we apply it. It's just learning for learning's sake.

I suppose it's no surprise that when people are finally given the option to learn in a practical way at the odd subject that allows for some project work most students can't seem to think of a damn thing they want to do. It's like a systematic suppression of creativity to make education more like a factory production line.