How can I stay motivated to eat healthy and exercise?

[NaturallyS]

I need to lose weight. This is my 4th time trying. Every time I try to lose weight it works for about a month and i might lose about 10 pounds but then I start get less inspired 2 keep going and I start eating all the junk food again and being lazy and not exercising. How can I stay motivated? Oh yea and it seems that every time my parents don't have junk food in the house it's easier 4 me to stay motivated and inspired but when they buy it it seems like i just wanna eat every thing... and I almost do! But I tried to get them to stop buying junk food and they won't. So trying too get them to stop buying junk food is out of the question. And I tried looking at motivational quotes but that didn't seem 2 help much.