It was also difficult for me to combine work and study. In the morning I worked, and in the afternoon or evening I went to study and took exams.
I believe that the main thing here is not to feel guilty for not being able to fully immerse yourself in the work. You are not bad and not lazy. You study and do it in order to work better and become a true professional in your field.
It is also important not to fuss and not be distracted by several things at once. Leave your thoughts about work after your working day and switch to study. Spend time on one of the most important items and only then switch to the next one. Plan what you need to do, make a list of tasks and actions. It helped me.