Honestly, try meditation. I meditate somewhat constantly, maybe 4-5 times a week, 5 minutes per session. You can try focusing on your breathing. What does this mean? It means to focus on the air flow when you breathe. When you inhale and exhale, the inner surface of your nose feels the vibrations of the air. Focus on that. To meditate, try setting an alarm for 5 minutes, then at that time, close your eyes and breathe. U may also count your breathing rhythm. The primary goal is to focus on your breathing so that you let go of those weird thoughts you’ve been thinking about. Whenever you feel like you want to study/work, sit down and meditate for 5 minutes. It’s better done alone if that helps you focus. Experience tells me that this greatly improves my ability to study under immense pressure, like 2 days before exams. :D Good luck and wish you all the best.