There's no "1 weird trick" that's going to get you the success that you want. It's the accumulation of action day after day, focusing on the fundamentals that will take you where you want to be. Decide where you want to go, why you want to be there, how you'll get there, and then do it!
Here is however one of my favorite techniques to help drastically improve the odds of your long term success. This isn't something that will help you see more results immediately, but rather help retain those results long term.
Everyone knows that your environment determines your thoughts and your thoughts determine your actions, so what I'm going to suggest is a simple trick for changing that environment that will mold your mindset and force your actions to follow.
Here's what I want you to do;
Instead of going from Netflix marathoning Stranger things and living a sedentary lifestyle to full blown workouts 5-7 days a week, try adding in "study days". Take 2 days a week between workout days and have it be dedicated "study time" just like you would dedicate gym time. Get out a good book on mindset, nutrition, exercise or anything that's motivating and educational for you and study it.
By doing this 2 times a week instead of going to the gym you'll change your environment in a way that fuels your inner fire regularly but also teaches you WHY you're doing what you're doing. It's a lot easier to not eat that slice of pizza for instance if you know and understand the nutritional science behind it.
Here's an example of what I've had people do when they start out...
Monday, Wednesday, Friday 4:00-5:00pm working out
Tuesday and Thursday, go to a dedicated place like a coffee shop from 4:00-5:00pm and study.
By simply replacing workouts 2 days a week with DEDICATED study time, you can change your mindset and drastically increase your chances at sticking to something long term.
If you give this a shot, make sure to send me an email after a few weeks and let me know it's going for you!