Try using your time in Covid-19 isolation to learn an instrument. Whether you choose guitar, piano, or didgeridoo, there are plenty of online resources (Youtube, Yousician, Skillshare) to get you started.
Learning an instrument is great work for your mind. It strengthens your reading, memory, and communication skills and can help ward off age-related mental decline. It also helps to ease stress and depression. On top of that, there's just nothing better than being able to play your favorite song, or any song for that matter, front to back all by yourself.
When you're in isolation for so long, it's normal for you to feel like you're stagnating. Our brains need stimulation after all, and if our brains aren't stimulated, then we become bored, agitated, and eventually, depressed.
Try using your free time in isolation to learn something new. There are tons of tools at your disposal for learning languages (Duolingo, Rosetta Stone), mathematics (Khan Academy, Ted-Ed), or even just general brainteasers (Brilliant.org) to get your mind working while you wait for lockdown restrictions to lift.
It can be very easy to feel lonely in Covid-19 isolation, especially when you're living by yourself. Try combatting this by hosting a party over Zoom. It's not quite the same as seeing your friends in real life, but seeing your friends, even just on a screen, will help to pass the time and lift your mood until restrictions in your area lift.
It doesn't have to just be talking, either. You can watch movies online with your friends or play video games together. Being connected and there for each other is now more important than ever, so video chatting (or talking on the phone!) is a great way to spend your time.