I just have to second everything that Lovely posted.
Losing weight isn't easy - if it was everyone would be thin. We wouldn't need forums like this! You say you really want to lose weight, but
just wanting it isn't going to make anything happen. Don't wait, your young. Get it done now so you can enjoy the rest of your life healthy and happy. Start small and eventually a healthier lifestyle will become second nature to you. Short walks like Lovely said.. and omit soda, stick to water.
Every time I would consider cheating I would think " Is this (fill in the blank - pizza, soda, etc) worth how unhappy I feel when I look in the mirror?" The answer was always no.
This is just a lil piece of advice from someone who wishes they had done this years ago. I am going to be 30 in a few months - my 20s were amazing but could have been a million times better if I had.
Good luck