I have cellulite and I am a pretty skinny girl, so go figure. Here is what has worked for me: combine some weight training with your cardio. If you firm those muscles (I'm guessing you are talking hamstring, quads and gluteus) you WILL see a reduction in cellulite. Get a loofah, soap it in the shower, and scrub. Also apply lotion after.
My second best treatment: I ignore it. Seriously. I figure I can't see the back of my thighs, so I pretend like it's not there. The only people it can bother is those who can see it, and I'm not one of them. Oh well.
Lastly, whenever I am on holiday, eating healthy and getting plenty of exercise, whether swimming, kayaking or walking, it definitely lessens. So I think stress and unhealthy eating habits play a role. Just my .02.