Rambling follows. I don't have time right now to edit this to be more coherent, sorry.

Move. Just move. I started going for MWF 5k walks, they took almost an hour at the start. Pick a shorter distance if that's too intimidating. A lap around the apartment complex at my old place was 1km. Do that once or twice each night after dinner. Make this a habit, a routine. If it's not, you can't take the next step to making a weight lifting or sports routine.

I also played soccer, badly. But I was moving. I'd give it all I had, get gassed, sub out, come back, repeat. Pick a sport that you enjoy and do it. Especially if you can find a group you like to play with. Going to the games was as much about seeing and being with my friends as playing the game itself.

Diet. My initial massive weight loss, I also quit sodas and candy. I eat and drink those now, but in moderation, as treats. This made the first 20lbs fall off fast.

Don't get frustrated by lack of weight loss. I'm back to 200 lbs (220->170->200 over two years). I got stuck at 195 on the way down. But I also added in BJJ which built up some extra muscle at that point, so I was trading muscle for fat. The way back up, it's been strength training (bodyweight) that's built up my chest and arms. I'm still fitting into 33" waist pants, so those 30lbs have been useful (170 was also too low for me, I looked emaciated, 180 if I'm just running, 190 with BJJ, 200 with those and bodyweight training are about right).

Accept that you may have many false starts. I "took up" running once a year or so for 5 or 6 years before it stuck. I took up bodyweight training with about the same frequency of starts and failures. This will be frustrating, but keep trying. And try new things. If you can't stick to the activity (for reasons other than injury or severe time pressures from other obligations), then you probably aren't enjoying it. Find something else.

Listen to your body and have good partners. I do BJJ, it's dangerous (NB: if everyone does everything right it's fine, but an armbar can easily screw up someone's shoulder or elbow if done wrong or taken too far). I started with a shoulder injury (soccer accident, body slammed by a teammate and landed on the shoulder). I didn't use that arm much. I tapped as soon as someone got it in anything resembling an armbar. I talked with my partners and told them the limits of my body, and they respected that. They'd avoid that arm during drills (or do it very light) and rolling. If you do something like this, and you don't have respectful, considerate classmates and instructors, FIND A NEW GYM.

Activities that can be fun to start with that get you some exercise, but you'll want more to get really fit and strong (if strength is your goal in particular):

Walking - easy to do, aim for 30+ minutes at a moderate pace to start. Then start shooting for distance once the 30 minutes is easier, and then reduce your time on that distance back to 30. That's why I do 5ks. It took me 50+ minutes to walk the distance, started jogging and got it to 40, started running and got it to 30.

Cycling - this will get you fit on its own. It's easy on the joints, slightly expensive (need a bike) and harder to do in inclement weather. But do the same as walking: 30+ minutes, then distance, then reduce the time back to 30-45 minutes (or whatever you can afford) at that distance.

Hiking - requires travel, but as almost as easy as walking, and probably more interesting scenery. Can be a fun social activity as well (let's go to the mountains this weekend!) or, if it's located near where you live, a nice thing to do with an SO paired with a picnic or something. Making being active fun is really helpful for sticking with it.

Dancing - ballroom, tango, they're challenging but fun and will help with impressing your partners in the present or the future. These can be harder due to needing to learn new skillsets and ways of moving and keeping time, but it's effective. Turned out to be useful when I tried my hand at boxing, too, with understanding how to stay light on my feet, control my balance.