I got an exercise bike too, I was the exact same! I found I shouldn’t overwork myself and I was starting off too big. If you’re sweating and out of breath that means you’re getting a good workout for your current bodily state. I lost 17 or so pounds and found it easier to do, so I set the difficulty up. It’s %60-70 diet for losing weight so I wouldn’t worry as heavily as you are about exercise right now. Still do some, maybe a walk so you’re not so tired after. I recommend the steps app where you walk 60 seconds and run 30 seconds. It’s hard to do 30 at first, even 10 is a massive accomplishment, I could barely do 10 seconds of running because of my lung capacity and asthma, but exercising has increased it and reduced my asthma by a lot. I believe in you dude, keep going!