reading out loud, making lots of lists (in lots of places too), taking thorough notes, studying in different places, these things that everyone else mentioned have been great for me.

I get bored quickly too, so I try to switch activities as often as I need to. You can switch between homework and other things you need to get done, or take a quick break to do something that's fun but not too engrossing (so it's not hard to get back to work). if I'm losing interest in the topic itself, sometimes it helps to watch videos (youtube, TED talks, documentaries) or listen to podcasts about it. doing that at the same time as you do your work might be useful (or distracting, it varies for me).