>>12193251turn off social media and distractions like 4chan (block em if you need to with someone you trust holding the key), drink coffee (safer version of stimulant abuse described in
>>12194213), and keep your professor's notes open, their lectures on a close tab, notebook on your desk, with everything else being empty space. Keep a lot of space to walk and pace. Try and come up with analogies to explain methods, mechanisms, proofs, phenomena, etc. Study in blocks of 3-4 hours with a 15 minute break every 1.5 hours within the block, and at least 1 hour break between blocks.
This works best for me. I have periods of being more lazy than productive, but getting yourself into the mood to study is largely caffeine + habitualizing jumping into "study" mode. Doesn't hurt to have grades and deadlines hurting your ego, but try to keep a healthy self image. Good grades and amicable relationship with your professor are the fruits of your labor.
Keep at least 2 days per week where you do nothing but relax. Violate this occasionally on crunch weeks but otherwise respect your limits.