How long can you do homework for without getting distracted? This is a big problem for me and I probably can only do it for 5-10 minutes before getting distracted.
Try using the Forest app to help you stay focused. If you don’t have a phone, they also have a Chrome extension. I have a similar problem; I can only focus for 20 to 30 minutes. If I need to go longer, I use the app. Otherwise, I just set timers on my phone: 20 or 30 minutes of studying, 10 minute break. If you always study in the same place, try changing it up. I study the best in a classroom after school gets out, and the worst in a vehicle with my friends on the long drives to ski races. It also helps to break your studying into manageable bits. For example, instead of “two chapters by Tuesday”, think “7 pages per day”.