I hear you, i do hate team based and competitive sports as well. Though those are not only type of sports you can do. There are sports you can do on your own on your own conditions and pace.

Now the main bodyweight changes come primarily from diet. Yes exercise can help with burning extra calories, but that should never be the main goal of it. “You can’t outrun a bad diet” does hold true, especially in moder world with calorie dense foods.
Now for dieting, don’t take it as a diet, because that gives an impression that it’s going to be done for a limited time. It’s more of a lifestyle change and shouldn’t be done in a one big change. It consist of baby steps spread out over months to years.
Already showing interest into it is the first step. Reducing portion sizes of some junk foods or switching out a single component can be the next step for the next few weeks.
Weight management and calorie intake should be taken as avarages on a scale of weeks to months.

As for training. The muscle pain you describe i assume is DOMs(delayed onset muscle soreness). Yes that will happen every time you put your body through a novel activity that exerts it. That can be reduced, mostly by starting slowly and for future motivation. With consistent training, it can disappear completely.
For example slow pace walking instead of running and slowly over the course of a month or two slowly increasing the tempo until by the end you are running, but minimized the novel stimulus part so that the DOMs would be minimal.

Walking, cycling, elliptical, low impact is good for overall cardio. Personally I’d recommend elliptical machine, mostly because it spreads out the overall load between the whole body and i can watch movies during it making it more interesting.

Other aspect would be resistance training. The most basic training, covering 6 movment types, spread out over 2-3 days is more than enough for overwhelming majority of people. No point to go nuts, with 5-6 days of training to complete failure and then be crippled for the next week and give up/burn out. Slow and steady wins the game. Start slow and ramp up over the course of months to years. Like it took me almost 10 months to go from training barely once a week to 5 times a week and then few more months to solidify the habit and fit it into ny overall life. Nowadays, nearly 4½ years later it’s a rock solid habit.

6 movment types, with examples would be.

• horizontal push(ex, bench press, push-ups, machine press)
• vertical push(ex shoulder press or even lateral raise)
• horizontal pull(ex any rowing variation)
• vertical pull(any lat pulldown variation or pull-up)
• squat pattern(bodyweight squat or any leg press variation)
• hip hinge (deadlift or any variation of it like RDL or SLDL or even good morning and/or hip thrust)

Those can be spread out over the course of 2-3 days, doing just 2-3 movments per day. One movment taking somewhere around 15-30 minutes. Staring out doing each movement once per workout to slowly increasing it to 3 times per workout. With repetitions, anything between 5-30 is good enough and has the same results, though preferably staying between 8-12 is better. Mostly because doing deadlifts or squats for 30 reps will exhaust your cardio first rather than target muscles, but doing 5 reps of lat raise can be rather uncomfortable if doing with free weights(dumbbell, barbell)

If you want let me know and i can help you figure out exact movements or alternatives for even doing those at home. No I’m not selling a training plan or am a trainer, just someone with autistic levels of interest in it.