41 year old female, 5'6" 122 pounds with 29% body fat need help!?

I am a size 4 or 6, used to be in good shape but have not exercised in 20 years. I have celluite, a spare tire, and squishy legs/thighs. I do not need to "lose weight" but I am way too soft all over and have rolls even! What do I do? I belong to a gym but not sure what to do there. I also have a bike, pool, and an eliptical. What would be the best thing to do to shape up?? diet?