In a diary, (it should be a diary) avoid your laptop or phone, they are huge distraction
Write down the main topics (like y/n has fever, ml took care of her) or anything that might be your content. along with serials no. That's very important. Topics as in the scripts that go number wise, In that way you can comprehend your next plotting and scence sequences even better. And you can later edit those para according to the suspension they might give to readers.
Now take your device, Simply write dialogue, (like "I'm sick") don't explain how it has been delivered then go on abreak for like some hour, eat something delicious. Read someone else book, it should be a textbook, they are well written.
Done reading other literature try to peek through the way that writer has described the way of their character's way of delivering dialogue. Only if you're okay with having some glimps and inspiration.
Create a soothing surrounding. Put on your headphones, listen to that one artist you feel like their whole playlist go better on your story. Try to focus in its lyrics and wording,
Now that only the dialogues are left to be described. Try to think how that particular dialogue must be delivered along. ( Like "I'm sick" y/n uttered slowly, her voice feeble causing ml to frown within confusion/ in confusion)
Done with dialogue and plotting arrange them better to create intrest and fun in reading.
I hope it helps.