Feeling Feelings Is Tiring

Hello! I have finally gotten the hang of feeling my feelings and allowing urges. The thought I have been using is “I’m feeling negative emotion right now and it’s okay; I don’t have to do anything about it.” So this is good news but after three weeks of doing this work I am so tired! Is it normal to feel extra physically tired from this kind of work? Just checking and hoping this will become a habit and less tiring over time. Thanks!