Weight gain is the result of mental and physical actions, conscious and subconscious decisions. In order to gain a significant amount of weight, you must choose to take specific actions: skip breakfast, snack on biscuits / chocolates / crisps etc, drink soft drinks, eat takeaways, drink alcohol on a regular basis, sit down and watch tv, waste time on social media, take sugar in your tea / coffee, ordering large portions, eating dessert, telling yourself you're tired and you'll do it tomorrow, believeing that weight loss is hard, etc.
My point in all of this is to get you to understand that it requires effort and consistency to gain weight. Now, some of these decisions are made on a subconscious level, but becoming consciously aware of these sabotaging habits is the first step towards a healthy weight loss.
Now that you recognise the time and effort that you've put into gaining weight, its time to shift that effort towards weight loss.
Make conscious decisions that result in weight loss: Eat a healthy breakfast, bring your own lunch to work, walk during your breaktime, snack on real food, exercise in the evening (walk, jog, sprint, hit the gym, do yoga, spin, go to a trainer, etc), have a healthy dinner, go to bed early, sleep well, wake up, repeat.
If weight loss is your goal, then your actions must reflect that goal. Weight loss is not complicated - the reason a lot of people fail to lose weight, is simply because they dont take the specific actions, over a consistent period of time, that place your body into a state of weight loss.
Take action now, the results are just around the corner.