Don't diet!!!!
5 years ago I was 220 and I'm 5'9". I couldn't walk up stairs my heart was getting irregular... I was diagnosed with a brain tumor.. So I said enough.. I took it on myself to get in shape or I would surely die.. I started slowley exersizing and took a couple adult skating classes.. Started eating right cutting out salt and fatty foods and NO snacks after dinner!! Started playing ice hockey again!! Took me 9 months but I lost 50 pounds... So it can be done..
So good for you for recognizing the need to change but don't diet!!... I'd start slow with simple exersizes like walking and slowely increase.. Maybe get a friend to go along... Cut out the snacks is a biggie!! You have to burn off more calories than you take in.. And you have to exersize.. Dieting alone rarely does the trick..
Don't think of it as going on a diet.. Think of it a a change in lifestyle.. You have to change the way you eat and get more active.. If you don't then when the diet is over, the weight comes back!!
