Why do I feel guilt about my posture being imperfect during meditation?

I spend the first five minutes of every guided session obsessing over my posture—is my back straight enough, are my hands correct? I worry that if my position isn't perfect, the meditation won't "work." This focus on physical perfection generates intense guilt and stress, which completely overrides the goal of relaxation. How can I let go of this perfectionism and accept a comfortable, imperfect posture? My name is Priya. DOB: 17th August 1996. Time: 10:20 AM. Location: Bhopal.