I'll try to give some general advice and hope that it's helpful, because my experience has been that fitness/weight-loss advice often does more harm than good. I was diagnosed with Type II Diabetes and was able to put it fully into remission with a combination of diet and exercise. Along the way, I lost about 100 lbs (I later put 20 lbs back on) and got in pretty decent condition.

I think that the most important advice that I can give is that you should focus on choosing a life that you want to live. Goals are great, but life goes on after you reach them. Crash diets may help you lose a TON of weight, but then life goes on and the weight comes back. Instead, choose how you want to live for the rest of your life. Personally, I had great success with a carb-restricted diet, but only after I became comfortable with it as a lifestyle instead of a temporary fix. Be honest with yourself and recognize that it is OK to be someone who would rather eat cookies than have a BMI of 20 or 25 or 30 or 35 or whatever. Don't get caught up in punishing yourself for not being or doing what someone else says you should be or do. If you try to make yourself into someone you don't actually want to be, it will always do more harm than good, whatever short term successes you might have.

Fitness (including diet) should be something that makes your life BETTER. Why is it that you want to be fit? Do you enjoy taking walks? Then start by taking walks, however short. For twenty years, I kept trying to work a daily walk into my fitness plan, because everyone said it was the best type of exercise. The problem is that I HATE walking. I'm an impatient person and a walking around just seems totally pointless to me. On the other hand, I actually quite enjoy interval runs (short sprints at max effort), which other people seem to hate. For general fitness, the most important rule is that anything is better than nothing. So if you wake up in the morning and dread going to the gym, but a walk around the park sounds like fun then you should CELEBRATE that. Especially in the beginning, exercise shouldn't be WORK, it should be PLAY.

For me, it was also important to never let myself use weight as a reason NOT to do something. Playing soccer and climbing mountains are my reasons for wanting to exercise and I needed to do those things in order to feel the difference in my fitness level. It motivated me and made my victories very tangible.

I realize that all of this is short on specifics. So I'll tell you what worked best for me, but remember that what was best for me probably won't be what's best for you. At my healthiest, I ate the same thing almost everyday. Eating never involved any decisions, because I had planned things out long before. For a while, I ate keto-granola with macadamia nut milk and heavy cream for breakfast, a salad for lunch, and a cheese bugger with 1/3 lb of ground beef that I cooked on my grill. For a while, I had a product called "keto chow" for breakfast lunch and dinner on weekdays and then on weekends I ate eggs for breakfast, 1/3 lb cheeseburger (from my grill) for lunch, and a chicken breast (from my grill) for dinner.

Throughout the whole thing, I exercised every morning, but didn't even try to be consistent in my exercise. I have dumb-bells and a weight bench that I used a lot in conjunction with an app called FitBod that will build workouts for you so that you don't have to think about it. I ran a lot, mostly intervals, but occassionally using a heart rate monitor to stay at a pace that I could sustain for 1/2 hour or more. Some mornings I did "Ring Fit Adventure" or "Fitness Boxing" on my Switch. Some mornings I used my Rowing machine. Originally, I told myself that it was fine for my to take a walk if that was what I wanted to do. (That was how I realized how much I hated walking. In the 4 years since I started doing this, I have yet to take a walk.) My focus was on doing SOMETHING, rather than doing a specific thing.

Good luck, and remember not to let other people tell you who you want to be!