Fast workouts aren't always the answer. Walking is an excellent exercise; it will tone up your belly, legs, hips, thighs, so cellulite isn't so obvious. Aim for at least 30 minutes/day, but more if you have time (minimum 30 min/day, 3 days/week). You don't have to run or job, just go at a good brisk clip. If you carry a resistance band, you can work your arms, shoulders, back all at the same time.
Yoga is also good for toning, tightening. Google it and you'll get a ton of videos that you can watch for free. The best yoga dvd I've seen is "Biggest Loser - Yoga for Weight Loss"........ you lose weight and tone/tighten muscles as the same time. I found mine at a department store for about $10. There are several different types of yoga; check them all out to see if you like one type better than another.
There are also some creams/lotions that will add collagen to plump up the skin, so the bumpy places aren't so obvious.
Of course, a healthy diet is essential for maintaining proper weight and good health, but diet, alone, won't get rid of cellulite. Even still, opt for lots of veggies, lean protein, good fats, whole grains, etc. You'll feel lots better.
Forgot to mention -- there's really nothing that will "get rid" of cellulite, short of surgery, but exercise that tones/tightens your muscles will go a long way toward diminishing it's appearance.