For me, the best results come with having a plan in place. I like to eat 3 full meals a day, and have 3 snacks throughout the day in between meals. A typical day looks like this:
5:30 or 6 a.m.: Breakfast (usually a breakfast sandwich consisting of 1 egg, 1 slice of cheese, basil, and hot sauce on a whole wheat English muffin or a toasted English muffin smeared with peanut butter.)
9 a.m.: Snack (usually a protein shake or a few light string cheese sticks with a fruit.)
12 p.m.: Lunch (usually a lean meat sandwich on whole wheat bread, protein chips, and a fruit.)
3 p.m.: Snack (usually 8 triscuits and a protein shake or a few sticks of light string cheese or homemade jerky.)
6 p.m.: Dinner (usually chicken, fish, or steak with a fist sized portion of a carb like quinoa or brown rice along with a vegetable. Occasionally pork chops, shrimp, or other fish.)
9 p.m.: Snack (usually fat free cottage cheese with a fruit or vegetable.)
These are pretty general examples but pretty consistent with the routine. There are plenty of other options over on my Healthy Eating link. The key is to have a schedule and stick with it. Give yourself some structure and something to adhere to, rather than just eating at random or when triggered. Random eating often leads to losing track or randomly splurging on progress hindering foods. These times are what work for me. You can modify it to your sleep and work schedule.
Next, it helps to prepare your meals in advance and pack your lunches. This has two benefits. You'll save money from eating out less and if you pack a healthy lunch, you'll stick with what you brought. Many times, when we don't pack a lunch, we're more likely to chase a craving or get coaxed into an unhealthy restaurant with a coworker. If you're always rushing in the morning, take 10 minutes at night before you go to bed to make your lunch.
Sometimes, more drastic measures are necessary. When I used to work one place, I was a stress eater and would go to the cafeteria and buy a couple desserts at any given time, sometimes multiple times a day. A) It got expensive. B) It gave more negative results in terms of physical wellness. I actually started leaving my wallet in my car so I couldn't so easily give in to my bad habits. Eventually you learn to get past your junk food cravings and stay on track. You can convince yourself you need your favorite junk food. But just as well, you can convince yourself you don't need it and choose healthy.
Lastly, if you still insist on going out for lunch regularly, know your options and choose wisely. Know where you can get a good piece of grilled meat with quality vegetables or a salad. And if you go out with a regular crowd, be outspoken and suggest healthy restaurants. If healthy restaurants are never an option, then perhaps it's time to bow out if you decide your health goals are more important. If they're good people, they'll understand.
Different things work for different people and you don't have to reinvent the wheel. But using these tips and having a plan can take you a long way in achieving your results. If you need to, before making a meal decision, don't think about what sounds good... think about what you're trying to accomplish and what sounds best in the moment that will carry you to your goals. Eat for nourishment, not indulgent satisfaction.