You're playing a long game here. If you order something at a restaurant, then find out the Chicken Caesar had 1,500 calories (Cheesecake Factory, look it up), don't freak out. It happens. Cutting 100 calories from your next few meals will probably keep you on track.
Also: nobody knows exactly how many calories were in your food. Just pick a number from the calorie counting app and go with it.
Your Body Doesn't Care What
Your Phone Thinks You Ate
On the topic of calorie counting apps: some people who enter foods in the crowd-sourced nutrition databases have unsound minds. They think they can lose weight by lying to their diary about how much they ate. Think critically about calorie content and portion size in those public databases. Strive for reality here.
Don't Get Emotional About Mistakes
Mistakes are mistakes. They aren't failures.
Decisions are decisions. They aren't cheating.
If you make a mistake or a decision you regret, don't beat yourself up, and don't compound it using the logic "I've already blown it today, so the rest of the day doesn't count."
Keep the Streak Alive
Good habits are just positive long term trends in your behavior. Even if you're not a healthy person, you can act like one. Plan just one day around acting and moving like a healthy person.
Then do one more.
Then do just one more.
As long as you keep the streak alive, you'll turn into the healthy person you're acting like.
Don't Do Stuff You Hate
Again: this is a long game and you shouldn't make rules you can't follow indefinitely. Maybe you go to a lot of kids birthday parties and you like cupcakes with sprinkles. Focus on whether the benefit you get is worth the sacrifices you'll make to balance it. Also, try not to go to too many kids parties, people will think you're creepy.
And don't eat bad food just because it's healthy. That's insane.
If you can't stand treadmills, but you like basketball... you get where this is going.
Your Plan Must Survive Contact With the Real World
Without a doubt, this is the hardest part.
Kids have after school events when you wanted to go to the gym. Sometimes you travel to a wedding and spend two days in a car and then there is cake. Find other time to work out.
You will end up at restaurants that don't have anything low-calorie on their menu. Hiding at home in a fortress of quinoa and non-fat yogurt isn't really an option. Just don't eat much at the taco stand.
I'm lucky to have an awesome wife who was willing to rearrange her plans to make time for me to go hiking. If possible, I recommend having an awesome partner, but I don't know what your Real World will do and I can't say what your solution will be.
Focus On The Positive
If you're looking better and you notice it, you should feel good about that. If someone else notices, practice your "aw, shucks" downward gaze and shuffle. Try not to smile too big.
If buying new clothes is interesting to you, buy a new outfit for every size along your path.
Admire your beautiful charts! I mean... I hear some people are into that. So if that's your thing, that's cool.
Let Me Know What You Think
I typed this up one night because a lot of people asked me how I did it. I didn't have a short answer, so I documented this (very) long one.
Is this helpful? What worked for you?