About this goal specifically, I found it beneficial to stop thinking about a target weight. Instead think about: What level of fitness do I want? What kind of health do I want? (the two are related, but not the same)
Main reason: If you take up exercise and are not obese or at the higher end of "overweight", you may not lose weight for the first couple of months (or ever!) depending on the style of exercise you've selected and your body's tendency to build muscle. If you take up weightlifting, and are overweight but not obese, you could see your body composition basically trade, nearly pound for pound, fat for muscle. You will look better and feel better but not achieve the weight goal, which can be disheartening to people who have an explicit weight goal even though what they've done has measurably improved their fitness and health. And if you take up running or something similarly cardio intensive, you may gain weight (building up leg and core muscles with running, for instance) in the first few weeks before any weight loss begins. This is similarly disheartening and demotivating.
Instead, think about what fitness or health level you want and why, then work towards them.
My fitness goal was predicated on being able to play back-to-back soccer games (rec league, 70 minute games). So I needed to be able to sustain nearly 2 hours of continuous movement including sprints and extended periods of running/jogging. So I took up running and got my 5k time below 25 minutes, then upped it to 10k runs. A single game left me feeling like I'd just finished a warmup, the second game would leave me feeling like I'd actually exercised but not fatigued.
My health goal was predicated on getting off a statin and reducing my blood pressure (largely work stress induced, but my weight and fitness at the time pushed it into the pre-hypertensive range). So I ate better in order to achieve that, and reduced (not eliminated, still drink coffee black) caffeine in order to improve sleep (both improved sleep and reduced caffeine also helped reduce my anxiety levels and my periodic panic attacks at the time left me, happy side effect).
Both of those left me at a lower weight than I started at, but I had no explicit weight target. If I had, I could've been demotivated by early weight gains (when I started running I went from 215 to 220lbs) or later weight gains (when I added BJJ to my exercise regimen I went from 175 to 190). Both of those were the result of increased muscle mass, but they both took me in the "wrong" direction if weight loss and a weight target were specific goals.
