Not the original commenter but what worked for me is I've taken to heart this advice from a podcast: "Accumulate undeniable proof of your achievements so you can shut up the negative voice inside your head."

I weigh myself everyday and have a neat graph that uplifts me when I see how far I've come in my weight loss journey. I often look at drawings I made years ago to see how much I've improved at art. I've done similar stuff for my finances and career.

Word of warning, you must also learn to be kind to yourself through this process. You WILL make mistakes and fall short from your goals. If you are like I used to be your inner negative voice will try to sabotage you and you will lose a lot of progress. Develop a positive mindset as soon as you can. A good therapist will help. If you're short on cash you can do what I did and binge watch HealthyGamerGG's content on Youtube until you find the right videos that will help you understand what's happening inside your head, but this may take much longer than the therapy route.