How do you deal with burn out

Recently resigned from my job and currently serving my 2 months notice period. Even though I have leaves to utilize, I only have enough leaves for a week.

Everyday I drag myself to work feeling I might cry and breakdown before I get to the office.

One of the reasons for the burn out would be the KPI. I feel that I was running at 100% capacity everyday and only hitting half the KPI which was so demoralizing cause I started to doubt if I was really hardworking.

After resignation I wanted to be like my seniors and chill out a bit hitting 50-80% capacity. But since my KPI numbers were already so low it would be pretty obvious that I was slacking. But I’m so tired and filled with so much anxiety constantly.

Any advise on how to deal with this burn out while I serve the rest of my notice period?