Hey, I'm completely with you - it's been an awful 2 years for us as sixth form students. Uncertainty and lockdowns get in the way of mental wellbeing. It is going to be difficult, but we're going to get through.
During the lockdown in summer I also lost all motivation, and am still kind of catching up from such a bad term! Many people are in the same boat. The things that have helped me are having a routine, utilizing our outside bit of exercise a day, and calling my friends - and even starting a diary has been great because I've been able to rant in it! Although, staring at a screen all day is so unhealthy but we have to do it to work - so our routines can never be perfect.
It's not long til the end of the year and the end of our school education! I keep thinking that this is what we've academically been working up to - and now we have CAGs - so everything we do now counts. Keep thinking about that - its almost over, and this last run is important - but whats the most important is our mental health. Exams can be taken again, things can be learnt at another time - but looking after yourself is so crucial. So, look after yourself and explore ways of best doing that. Staying active, sleeping well and eating enough is crucial. And don't always think about work or stress about it - make sure you have lots of times to do what you love, like listen to music or watch a film etc. We can get through this, we only have a few months left, and hopefully a few of those will be in person at school!