I was 240lbs at 16. (and 5'11). Enough was enough, and in two and a half months I 180lbs, then a month and a half after that I was 175, where I have floated around for the past 8 years (At 6'0)

Let me tell you, the road ahead if you're serious isn't easy, but it is very rewarding. You won't feel tired anymore, and you won't feel trapped in your own skin.

The first biggest change you can make is diet. A good diet can survive a hiccup, but you can't out exercise a bad diet.

Cut out non-diet Soda. The Diet variety isn't exactly great for you because of the chemical shenanigans going on behind the scene, but it can be helpful once a week or so for a feeling of satiety. Water is best, it's literally what your body needs.

Keep excellent track of what you eat. All the planning in the world doesn't help if you don't eat at a caloric deficit. That is, absolutely, the only way to effectively lose weight. Plan, and eat at, a modest caloric deficit. Tools like https://www.myfitnesspal.com/ are something I wish I had. (Important to note, some of the items in there are crowd sourced. Read the packaging to get a sense of what you're actually eating)

Introduce exercise gradually, but aggressively. You're going to be sore. REALLY SORE, but don't worry; with proper eating, you'll feel better. I biked. Everywhere, and at least an hour a day at a moderate pace, something that elevated my heart rate, but not into a rate where I felt like I wasn't in control anymore.

For the first two weeks, you are going to feel hungry. Push past it. You're not really hungry, you're just not full, for the first time IN a long time. Drink water, go for a ride. BUT DON'T STUFF FOOD INTO YOUR MOUTH.

Most of all, when you do eventually lose weight adhering to this advice, don't slip back. A diet isn't temporary. It's what you do for your life. Only a positive, permanent change will lead to lasting results. There is no temporary fix.

Good luck.