well I find it helps if you keep some sort of schedule. Find at least one thing that you are looking forward to doing and schedule it in, so that there is something to look forward to. Also for school, create an area to do your work that is separate from where you relax. When you enter that space (whether it is a nice chair, a completely different room, or the other end of your bed) you are at school. I know from experience that it can be tricky to get motivated- especially now with all the quarantines. Sometimes you just have to realize that it is going to be a less than motivated day. Just don't beat yourself up when it happens.
Keep in mind that the pandemic will come to an end some day. Before then, quarantines will be lifted (hopefully with safety measures and protocols in place) and life will pick back up. This will all be over one day, so don't give up, but also don't be afraid to take breaks when you need them.
Here's a tip for motivation that got me into college. Get a timer (do not use your smartphone). Clock works too, but a timer is better in my experience. Set yourself a time limit to finish your assignment or studies. Say, 2 hours to memorize a page that's going to be on a test. It's definitely okay to get past the time limit. The point here is to give yourself a little push.
That's what I do for quarantine work. Like, "finish this assignment by 10 am". I'm definitely capable to finish things quickly, but I procrastinate a freaking ton (it's 1 am and I still haven't done Friday's work). It pushes me to finish so I can goof off on here.
What you're suggesting reminds me of a thing I came across lately, called pomodoro or something like that. You're supposed to set a timer for 20-25 minutes, get a task done in those minutes and then take a rest for 5 minutes. After four times you take a longer rest. It seems to work for me, especially because it makes me work towards a goal and I won't be able to get distracted.