Cardio, lots of cardio, but also involve some weights. Nothing too major, but some work with dumbells will tone your flabby skin up and develop your muscles further.

Also avoid high calories, high fat, and high carbs. Everything in moderation really is the key, don't intake too much salt or sugar either. Home cooked food is healthier than already prepared food. Avoid seasonings that have salt in them, instead opt for herbs and spices with no salt at all.

As far as cardio, walking is not a enough, and neither is jogging. Do a mixture. Powerwalking, then sprint, then just walk, then jog, and vice versa. Get your heart beating, get your entire body working, and your bloody flowing.