I have a few tips:-)
Drink water (add lemon and mint too)
Stay away from junk food like crisps and sweets. Instead eat fruit with honey and nuts.
If you are keen on chocolate, try a dark chocolate
Try to work out everyday (even 10minutes as soon as you wake up makes a big difference)
http://www.glamour.com/health-fitness/2012/03/get-a-body-like-lady-gaga-in-four-weeks?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+glamour%2Fhealth_fitness+%28Glamour%3A+All+Health+%26+Fitness%29&utm_content=Google+Feedfetcher#slide=1

I like skincare, so focusing on skincare has caused me to stay healthy. What I know is what you put in your body , shows up outside eventually, as you are now seeing with the junk food and weight gain..
If you are willing to dedicate your time, body, and energy to this, then you need to be willing to work for it , laziness in any way won't help. I've learned this:

First stop with the junk food, you're going to have to consider the food pyramid, not extensively but just try to get in something from each of the main groups a day. Fruits, nuts, meat/protein, dairy, etc. 3 meals a day.

Next, you might want to consider vitamins and supplements. They will give you a boost in whatever you may need, and keep you feeling healthy. For my skin, I personally take:
omega 3 fish oils (1000mgs)
vitamin A
vitamin C (1000mgs) and vitamin C crystals
vitamin D3
vitamin E (2000mgs)
Biotin
Alpha Lipoic Acid
Coq10 (collagen)
Iron (for my iron deficiency as perscribed by a doctor)
N-AC/MSM (powders for skin, hair, and nails)--
and Jarrows Reduced Nano-Glutathione pills

All of them separately (not in a multivitamin) . Not only do they have health benefits, such as boosted immune system, helps with staying focused, helps fight free radicals and serve as antioxidants, they also have beauty benefits, brighter, clearer, and more fuller elastic skin.

Next, you should definitely consider exercise. 3 -4 times a week for 30-40 minutes. Reading magazines and going online won't help. If you don't develop a routine and stick with it religiously. It's not simply 1 or 2 tips, it's a whole routine you need to make and you need to change your lifestyle. It's a lot of work. Excercise can be as simply as dancing, or pilates. On youtube there is a type of dance exercise called para para, which is japanese. It really helps to tone arms and serves as cardio if you do it on heels. It's fast and difficult to learn.
Examples:
http://www.youtube.com/watch?v=gjQiiHOK7K4&
http://www.youtube.com/watch?v=N83OgbV0zrY&
http://www.youtube.com/watch?v=TnnVXuvU-Cc
http://www.youtube.com/watch?v=17kKCndHMu8&

If you can't enjoy exercise then you won't want to continue, it'll be like a chore you hate doing. Which is why it's best you do things that you find enjoyable, which will also benefit you health wise. Para para , is dancing with the benefit of getting fit. You can do it alone or in groups, and practice daily for 40 minutes or so, and through that ,you get the amount of exercise you need.

Youtube pilates belly routine

Staying busy works for me,I'm so tired when I get home that I don't notice the junk food.lol : )

we all need to detoxify our bodies just drink 8-10 glass per day