Hello, distraction and stress are the main culprit here, yes you can avoid both. First avoid smoking and drinking if any and too much of caffeine drinks. Eat timely fresh foods avoid junk or fast foods. Atleast 6-7 hrs of quality night sleep should be there and avoid over sleeping. Meditate for 10min morning and evening, in a park or calm place. Sit for five min as soon as you get up and while you retiring to sleep in night sort your what are your destrations and why you want to study, and think about organizing work for the day or next day. Talk to your fiancee about any issues get her suggestions too. Drink plenty of water. Important is keep time table to work or two study and don't worry.