I've experienced severe burnouts several times and had the same symptoms as you. First and foremost, it's essential to understand and find the cause of it. Burnouts are an emotional and physical state, which are caused by prolonged or repeated stress. My first suggestion to you is to find the source - is it the work environment, is it because you are feeling overwhelmed, or is it because of a personal matter? Whatever it is, it's crucial to identify it as soon as possible.
The next thing you can do is to take some time away from the computer. It was already proposed by many, and this is no coincidence. We are living in a fast, everchanging world, where a work-centric life full of overtimes is becoming the de facto way of living. Many find themselves in a vicious cycle of monotony, which is another reason for burnout. Step back for a while and try something different - try traveling, start reading non-tech books, find a hobby, or take a few days off and do nothing. You will return a changed man!
Healthy body healthy mind
Exercising can improve your mood, confidence, and well-being. It can also help you cope with burnouts. It can boost your energy, sharpen your focus, and relax your body and mind. Meditation is also an alternative that can work for you. Whatever you choose, make sure you are consistent. The results will come soon enough.
If you still can't find the motivation to work on your side projects, try to split your work into small, deliverable chunks that you can deliver in minimal time. Try to maximize the feel of accomplishment by successfully achieving short, but meaningful work. That dopamine rush of shipping can drastically increase the feeling of making progress.