How to be Healthy with ADHD!?? Tips Appreciated!!

Hi all! I am new to this sub, and boy I have never felt so seen. Everyone seems to helpful and has great advice about managing their ADHD. I wanted to see if anyone had tips about being more active and eating better? I feel like I hyper fixate on losing weight and getting better for a little bit, and then I crash and burn. I’m just trying to be more active and feel better but I can’t seem to make myself be productive. On top of that, my main source of serotonin is a “little sweet treat.”

I am going to a doctors appt to try and get on meds. Has anyone seen a significant difference in their eating habits and active lifestyle on medication?