Surrender vs. resignation

Hi coaches, could you help me see more clearly the difference between surrendering, this kind of act that we often hear about in the self-growth world versus resignation?

I am exercising and eating to affect how my body looks. If I were really accepting it and loving it, I could surrender to it and not feel the desire do modify it any more and allocate that energy to other important things in my life. However, if I said to myself now “be adult, look at your priorities and prioritize your efforts to things that truly matter to you”, it feels like resigning to a shape of my body I like less.

I have noticed that fasting triggers intense resistances. I am doing work to allow feelings and sensations to be there. I could surrender to the fact that fasting is not for me not right now and eat differently. But so far, this feels like resignation, giving up, defeat, like I am at the mercy of acquired responses and being triggered is always around the corner. I would be grateful if you could help me clarify the difference! Thanks.