Exercise motivation?

Anonymous
I really need to lose weight, but I don't have any motivation. I just sit at home all day and watch videos on my computer. I am 15, with a height of 5'5". My weight was last seen at 143, but that was several months ago (I don't have a scale). In other words, I'm FAT, and I don't wish to be. My clothes don't fit me, and I can't wear them like I normally do without my gut getting in the way.
I've had an eating disorder in the past, and I did try healthy eating too, but I don't have enough self-control to stay away from the junk my family buys. They only buy soda, top ramen, and other junk. My attempts to ask for healthier foods didn't work; processed garbage is much cheaper, and we're not wealthy.
What are some tips to get me to start my day right? How can I motivate myself to wake up and begin stretches/exercises? That's what I'd like to do. I want to wake up early, make a cup of tea, and exersize, but I can never break out of my lazy habits. Sometimes I have insomnia, too, so getting up early just isn't an option.
Please help me. I never want to become obese, but it's so easy to do in the United States.
Exercise motivation?
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