During study how do I get back to or keep focused when my mind wanders?

During study how do I get back to or keep focused  when my mind wanders

Remember that your attention span is seldom more than 20 minutes - often, especially when you are studying something that you don't enjoy it could be far less. So get up from your desk, get a glass of water, maybe do your cross over exercises and then go back to your PP (with your baroque music playing in the background) and then count yourself out to 1, 2, 3 to return to move on with your study. When you are in your PP you could tell yourself that you like the subject and that you are enjoying  finding out something about the subject you're studying. When it happens again then do the same process again - after that study something else. In other words study the subject that you like least in short bursts.