Distraction is an easier problem to solve than boredom. You can avoid getting distracted by removing potential distractions from your environment. If your choices in the room are to study or stare at the wall, chances are, you’ll grow tired of looking at the wall sooner or later.
You can also help your focus by studying in bursts and taking regular 5 – 10 minute breaks every hour or so. It’s easier to stay on topic when you know how close or how far you are from finishing the current study session.
As for boredom, to a certain extent, that’s unavoidable. We all like different things and we can’t just learn what we’re personally invested in. That said, you can mitigate that problem by trying different learning materials. Maybe try watching videos instead of reading, or hiring a private tutor if that’s a possibility. There are plenty of quality learning resources online, as the GAMSAT preparation material found on this page shows.