You're probably anxious about the future right? / maybe depressed about how alone you are? How you might always be alone? Getting beat up by nostalgic thought?
The anxiety and depression are giving you head cloud. Counteract the anxiety and depression and you will be able to focus again. Some options:
if you're really thinking it may be something worthy of psychiatric attention, get anti depressants.
feel unable to focus? Calm your atmosphere down. Find some ambient music, maybe some kind or studying music off youtube, nothing sad and nostalgic that reminds you of your ex, something new and without lyrics. Calming tempo. Get a plant, soft lighting, clear your desk etc.
sleep more and better. I do guided relaxation before bed and wake up feeling way better than if I don't. Helps my focus better than anything.
shitty emotions get shittier in the evenings, idk why. So does your ability to focus. Work when you wake up. Then revise before you got to sleep so ur memory files it all away overnight.
exercise. The best drugs are already in your head, waiting to be released. Go do cardio to feel better and more focused almost instantly. Also helps self esteem. Weight lifting if ur a guy will help ur self esteem make you feel a little less like the slowly rotting byproduct of a failed relationship. Anecdotally, don't overdo the weights. 45 minutes of workout feels good for me. Anything over an hour and I get inexplicably anxious. Something to do with cortisol maybe? Idk, I'm not that kind of smart.
self help books. Even if it kinda reads like bs it can remind you that things are getting better. A good one: The Road Less Travelled. Got a copy on my self lend it to all my sad shitty friends. All three of em.
probs something to be argued for going out and getting laid. Idk about that, haven't tried. I'm too delicate emotionally to handle that if I Fuck I up. You may be different.
drink a lot of water. Why not? Worst case scenario there's some more water in you.
change it up a little. Scenery, your outfits etc. You wanna move forward? Change some shit. Two month is a long time to still be dwelling. Go buy yourself a new coat, grow a beard/do ur hair different. Just do something man/woman.
I for one subscribe to adderall/clonazepam Fridays. A lovely combination. Makes me feel like a firetruck. Get a lot of stuff done in a day.
clean up your diet. Sugar and caffeine aren't as good as you think. Leave caffeine for the emotionally healthy people. Leave sugar for the people who don't understand diet.
I take vitamin d3 supplements cos like everyone in canAda is supposed to be deficient. Also omega 3 fish oil. Haven't noticed a marked change since fish oil but it can't hurt. Supposed to be good for your brain. Idk what else I have to say. Stop talking to your ex maybe. It's over dawg. This is the time to be selfish. You build yourself up bigger and better. Make all the other dogs wants you. Especially when you got a sweet career after you studied so hard in school. It's Friday btw. Sorry if this is nonsense.