But at the same time, you need to be able to buckle down and work through these struggles. And oftentimes it requires you to slow way down (either by using a metronome or slowing down the actual MP3 track), work on making your movements as natural and efficient as possible, repeat it until you can play it slow in your sleep, then gradually speed up.
I spent 3 months once working on speeding up a lick that's only two seconds long. And now I'm much faster because of it. I only sped up 1 bpm every couple days.