New belief vs. really big goal

Hi! I’m working on a weight loss goal. I’m wondering if I need to make my new belief for this month on that goal, or can it be on an unrelated topic, like relationships? I know that these relationship issues cause massive heartache for me and that can affect my eating as well, so in a way, I feel like a happier heart will help in the long run with the weight loss goal. Will I be working on that new belief for the rest of the year too? Am I losing focus by working on this other thing?