As far as I know, the breathing meditation that you're doing now is fine. Naval referred to meditation that involves something more complex, like, say, three seconds in, five seconds out, etc. and counting that.
Also, note this:
If thoughts come, thoughts come. I’m not going to fight them. I’m not going to embrace them. I’m not going to think harder about them. I’m not going to reject them. I’m just going to sit here for an hour with my eyes closed, and I’m going to do nothing.
So it's not about sitting there and thinking whatever. You try to be a passive observer. You don't entertain the thoughts, you don't fight them, you don't follow them. Just sit and observe in whatever way works best for you.
At least that's how I understand it and plan to approach it.
Also, here's an excerpt from Naval's interview with Tim Ferriss that may explain it better (I put in bold the key piece of advice):
Which is you sit there for 60 minutes. So unfortunately not less than an hour at a time, because it takes 30 to 40 minutes to sink in past the initial chattering. So you get to the good part or the so-called runner’s high equivalent. And you sit for 60 minutes every day and you do it for at least 60 days. And you do it first thing in the morning. When your mind is clear and you’re alert and you’ve had a good night’s sleep.
And you sit up with your back straight and you can use cushions, or you can use a chair or whatever. There’s no magic position. And just whatever happens, happens, whatever your mind wants to do, you just let it do. If it wants to talk, you let it talk. If he wants to fight, you let it fight. If it wants to be quiet, you let it be quiet. If it wants to chant the mantra or pay attention to breathing, you can do that, but you don’t force anything.
You just kind of let it happen. And so you don’t fight it. You don’t resist it. You don’t argue with it. You don’t double down on it. You just kind of let things happen. And when you do that for at least 60 days, my experience has been that you kind of clear out your mental inbox and all the craziness that was going on. All the chattering will come out. Some problems will get resolved. You will have some epiphanies. You will make changes to your life.