How can I get my 12 year old brain back

I was overweight as a child and suffered emotionally for many years because of it. During the summer between my 7th & 8th grade year, I just decided that I was done being fat and lost 30 lbs….just like that. No drama.

I am now 50 and have struggled with my weight since I had a baby at 35. I make progress on my goal to drop 50 lbs and lose 10-20 lbs but then slip up and gain it back. Painful pattern over these past 15 years.

How can my 12 year old brain figure out how to commit to dropping the weight and get it done but my 50 year old brain thinks it is a terrible idea and fights with me everyday.

I’m so over this. Need your wisdom.