Your challenge here is to avoid focusing on the product—the solved homework problems. The product is what triggers the pain that causes you to procrastinate. Instead, you need to focus on the process, the small chunks of time you need over days or weeks, to solve the homework problems or prepare for tests. Who cares whether you finished the homework or grasped key concepts in any one session? The whole point instead is that you calmly put forth your best effort for a short period—the process.