Your weight gain, in most cases, is the result of poor decisions you've made about what to eat and how much to exercise. No one held your mouths open and poured food down your throat. You need to recognize that it was your decision. But you can change your mind.
Just as the decision to gain the weight was a personal (although unrecognized) one, so is the decision to lose it. And make no mistake: it is a decision - an active, conscious commitment that, given time, will become a subconscious habit. Like any habit, proper eating habits and a healthy exercise regimen take time to develop. During this time, be especially kind to yourself. Give yourself the same patience you would give a toddler, just learning to walk.
Once you realize that you are in control of your destiny, once you accept the responsibility for your own weight, you will find yourself more prone to making smart food decisions - and less likely to skip exercise. After all, someone, whom you don't want to disappoint, is depending on you - you.