Plan ahead. When and what you will study - divide your day into 40-60 minute blocks. After each block, take a rest. Go for a short walk, do some exercise and/or take a coffee break. Have proper meals. Your body and mind can only “work” properly when it is properly fuelled. Do the most difficult tasks at a time when you are most efficient. If you feel your brain is buzzing after hours of hard study, you will find it difficult to concentrate on a complicated piece of work.