I lost about 40 lb and have kept it off for many years. I wasn't really trying to loose weight - I was trying to control my migraines. So my motivation was to be in less pain, which for me is more compelling than loosing weight.
The biggest thing I changed at first was cutting back on sugar, refined grains and highly processed foods. I didn't worry about fat, carbs or calories. For a year I was very strict - I ate nothing with added sugar, no bread, no pasta and so forth. After the first year or so I cautiously added some of the foods I'd cut out back in. I became more focused on eating whole, natural foods than avoiding food. I still didn't worry about fat, calories or carbs. I continued to loose weight over the next few years, then leveled out at my current weight
The suggestions above are all really good - make it easy to eat the good stuff and hard to eat the bad stuff. I keep a big bowl of salad made up in my fridge as my go to snack. I love to eat salad with nuts... Ok, I'm getting distracted by food.
Try to get as much fiber from natural sources as you can. To keep yourself motivated set really easy goals for yourself and give yourself a little reward (non food) when you meet them. If you can make healthy eating a habit, you are much more likely to stick with it.
If you do all this you might or might not reach your goal in weight loss, but you will definitely feel better and be healthy.
Oh, and holidays mess me up too. I ate Way Too Much Easter sugar