I can’t wrap my mind around not exercising being healthier for me. TW

I’m just extremely frustrated with myself. I can’t follow my meal plan, it’s an insane amount of food and I can’t do it. I feel like if I was allowed to exercise then I could get closer to following my MP but the only thing I’m allowed to do is short walks and gentle yoga. I feel like my whole life it’s been pounded into my head that it’s unhealthy not to exercise so how am I supposed to just not exercise and not feel guilty about not exercising? How am I supposed to not feel guilty about following my meal plan AND not exercising?