I constantly have a conversation with someone who would ask me how long I'm on a diet for and I always respond with something along the lines of:
People are sometimes under the impression that to lose weight takes a great deal of effort for the next few weeks but then afterwards you can relax , but that's not how it works. If you have battled with your weight and want to either lose or gain weight you have to make a complete lifestyle change. Staying away from your favorite desserts is not something I would encourage. Instead have less of it or allocate an 'off day' where you can indulge (not overly) in your favorite foods. Making a lifestyle change should never feel like a job, but you must make the sacrifice. If you keep eating the same things and leading the same lifestyle you're not going to lose that weight.
Take control, make the sacrifice and make it last.
Even with the exercise make it a part of your everyday living.