39 here, been battling the up's and downs since I was 14. I feel confident that this time I can do it and maintained because the changes I have made have been small and undramatic. Over the last 25 years I have learned to heat a fairly healthy lifestyle, mostly I just try to make sure I'm eating food, nothing too processed that I couldn't make at home if I wanted to. Over the years depression has lead to many gains and even a few losses but it was always back and forth between "Yay, I'm skinny! Quit exercising, eat whatever" "Boo, I'm fat, exercise your ass off and start crazy diet, lets lose!".
About 5 years ago I "broke down" and started taking antidepressants, I say "broke down" because from the time I was 20 people told me I was "stronger than that" or "just exercise, it's as effective as anti-depressants". Medication was a huge help, mentally, but weight wise not so much. For the first time I was ok mentally, happy even, and I didn't care about my weight and having a perfect body.
My weight went up to 190lbs and while I wasn't stoked I was ok with it. I learned to love my body, but I really learned to love my old 150-165lb body and missed it and wish I had loved and appreciated it at the time instead of just hating myself the entire time.
With that new self love I found a great partner and started a new career. After a little bit of cooking at home and eating less crap I dropped down to 175lbs and then down to 160lbs. And then a major depression hit. I gained 15lbs back and decided that for reals, I was going to get this aspect of my life under control. I dropped a few pounds and then found this subreddit, downloaded MFP and haven't looked back.
Currently at 145lbs with 10lbs to go until my goal. This time around I didn't make any major changes I just figured my TDEE and tried to eat 15-20% below that. I'm running again, but it's still very on and off. I'm coming out of a 4 month depression where I still lost 5lbs by just not quitting or giving up. I know exactly what will happen if I quit, I've done it dozens of times. So this time I'm just plugging along, I try to keep days where I struggle to just below or at maintenance and just keep trying. I just logged 200+ days in MFP and have accepted that like depression, anxiety and alcoholism my weight will be something I manage for the rest of my life and that's ok because I finally have the tools to make it work.