First Day

20 pounds by thanksgiving is probably unrealistic. The fastest rate of loss is 2 pounds per week, and that is not advisable (or even do-able) for most people. Typically, a half a pound to a pound and a half per week, depending on how much you have to lose, is what you should be targeting. Losing weight at a slower rate may seem a bit discouraging, but it also means statistically, you are more likely to KEEP it off. And whats more important? losing it fast? Or actually KEEPING it off once you lose it?

The key in losing weight, and take this from someone who has lost over 192 pounds, is to make small, SUSTAINABLE changes. this is a long term effort. not a sprint. you will not lose weight fast. you will not lose weight every week. you will have weeks on end with NO weight loss. its normal. trust the process.

my main tips:

learn how to weigh (on a food scale) your food properly and find ACCURATE database entries now. I don't know what your starting weight is, but at first you may have a lot of room for error. but as you have less to lose, you don't. If you learn how to do things properly from the beginning, it means you don' have to RE-LEARN how to do it later.

Find an activity you ENJOY. You don't have to be a runner (ew). You don't have to work out at all to lose weight (weight loss happens in the kitchen). BUT... physical activity does have a LOT of benefits. Both mental and physical. It can be as simple as a leisurely stroll a few times a week. And as you lose weight, you may find (I did), that you WANT to do more. Simple, little things like parking a bit further out in parking lots. Taking stairs instead of elevators. walking to your mailbox instead of pulling up to it in your car as you are pulling in your driveway. Small things. Every bit counts.

Understand that you do not have to give up your favorite foods or any food groups to lose weight. You DO need to learn how MUCH you can eat. Portion control. This goes back to my first point. For the most part, I eat the same things I always have. Just less of them. I eat burgers and pizza and chips and cookies. Just ... not all in the same day well, I might could get away with it if I planned it out REALLY well. And stuck to the plan with NO deviation. Maybe. LOL

You will have 'bad' days. Whether its a holiday or just a ... bad day. Life happens. you will go over. It is NOT the end of the world. You will not ruin your deficit with one bad day. The problems come in when that one bad day becomes two, becomes 3, becomes a week, and goes on....

You've got this. Take it one day at a time, and each day, try to do a little bit better. Don't try to do everything all at once. Don't try to make 1000 changes all at once. Most people who burn out, do so because they try to do too much, too soon. start small. build from there. You did not gain the weight quickly. You will not lose it quickly. Better to lose it slowly, and KEEP IT OFF, then lose it quick, and gain it all back and more!

I've been at this a long time. It becomes a part of your life, and like any other habit, you don't think about it much, really. Your eating habits slowly change. You weigh and log your food. Your activity levels (usually) change, at least to some degree. You become more mindful of what you are putting in your shopping cart and body. My one (or two) words of caution is to make these changes slowly. Most people who go 'All in' head first and full steam, burn out quick. Your first couple of weeks, maybe even first month, most people will lose a fair amount fairly quickly, but most of it is water weight (usually from a reduction in carbs). It does slow down, as your body adjusts. It's normal, and is SUPPOSED to happen, so don't get discouraged. Also, don't set your calories too low. The fastest rate of loss (1200 for women and 1500 for men) is not the best rate of loss. Although very tempting to set it to lose faster, it will make it harder for you to maintain and stick to your calorie goals because you will be ... well, hungry. Be kind to yourself, give yourself a few more calories, and you will still lose weight and be less likely to deviate from your plan and therefore more likely to succeed.

Useful Links
https://community.myfitnesspal.com/en/discussion/1234699/logging-accurately-step-by-step-guide/p1
https://community.myfitnesspal.com/en/discussion/1296011/calorie-counting-101/p1
https://community.myfitnesspal.com/en/discussion/10683010/the-weird-and-highly-annoying-world-of-scale-fluctuations/p1

and basically ... all of these

https://community.myfitnesspal.com/en/discussion/10300319/most-helpful-posts-general-health-fitness-and-diet-must-reads#latest

@Lioness_2021 There really aren't any "tricks". Forget will-power, motivation, "diet" mentality. Those will all fail you. What will work, really work is developing healthy HABITS. Develop the habit of tracking what you eat and drink. Develop the habit of making healthy food choices. Develop the habit of getting off your keister every day and moving. That will set you up for losing weight, getting fitter, and not having to fight it every day. Just like brushing your teeth is a habit. Taking a shower is a habit. Buckling your seatbelt is a habit.

Hope you are successful in your fitness adventure.

PS I have a drill-sergeant mentality, sorry!