You've been taught all your life to be pushed to be strong.
But we are human beings. Even the machine cannot run 24 hours, nonstop for weeks, it will collapse. You have done too much to your body in all your lives, so now just relax. If you feel tired the whole day, do the breathing, and bring in more oxygen into your body, why? The more oxygen you bring to the lung, the more you energize the body.