By experimentation. By trying it out.
By doing it. With the right mindset. And giving it enough time.
There are a gazillion options for fitness out there. There are umpteen diet protocols. And there are more and more people on the coaching side of things, as the fitness landscape opens up.
Inevitably, everyone starts to sound the same. The promises. The bravado. The 6-pack. The allure of transformations.
There are success stories in EVERYTHING. Including the most non-scientific bro-science methods out there. And there are failures - including in the best training protocols out there.
Because it all comes down to you.
As Coach Dan John says, there are many 8 weeks in 10 years. So, don't be in a rush. Pick one that resonates, talk to a couple of people in the community, talk to the coach - and jump in. Do it for 6-8 weeks and see how you like it. If you are okay with commitment, commit to a challenge - a race in 6 months, or a 6-month membership or whatever.
Before results, focus on effort. Just show up. Even if it is boring. Coz it will get tough and it will get boring, sooner or later. But keep showing up.
And after that, you will be a few steps ahead of where you are. And if what you are doing currently is not your cup of tea, don't force it. There are a lot of options out there, and you know a bit more about yourself now. Find something closer to your wavelength.
In a few attempts, in a few "8 weeks", you will get there.
Find YOUR thing.