How to work only 8 hrs. a day?

Been working 12+ hrs. almost every day for the past 2 years. I don't feel that I have learned anything new last year. The Organisation that I work for is using very old tech stack. I have to admit that I am getting good appraisals. I kind of feel that they are trying to trap me here. I have tried to stop working after office hours, but after 2/3 days I lose steam and go back to working from home.