Do you struggle with energy? After continuing to work without a break, do you get to the stage where you feel you need to sit out or down? It may be after a workout at the gym or after lunch. Perhaps when you reach that stage it’s worth you assessing what you do.
Taking rest first, then continuing to go about you day, should give you that little bit more energy, but pushing yourself without a rest, may make you even more tired.
Whatever you need to do, it will be best done when your body is ready to let you. When you work in harmony with your mind and body, it makes for a more peaceful life.