How do I stay focused for 8 hours a day?

I’m having problems adding productivity to my daily schedule with work. <br><br>I’m 30. I’m home all day because I’m a remote software tester. We are remote due to the pandemic. <br><br>I’ve been working remote now for 5 months. I’m having problems being productive during my work hours. <br><br>I want to be productive all day, but I’m worried I will burn out. I’m not used to working this much. <br><br>It’s the weekend and I’m doing a lot on weekends but I want to be productive during the week. <br><br>I’m kinda stuck and I need advice. <br><br>I’m also worried about my health. I’m 30 and I’m not used to working all day and I will exercise 3 days a week.