I could perhaps talk about my experiences.
I’ve been meditating for over 25 years now. I started considerably young, because I had terrible migraines and the only thing that could help me was deep meditation.
So I’ve had some funky experiences along the years with various meditation techniques, bulk of which were completely outside of anything buddhist, mostly standard psychotherapeutic / self hypnotic tools. A lot of breath exercises.
Now, breath exercises are not specifically breath meditation. I’m used to controlling the breath, but I’d never practiced just attending to breath without assuming any control. When I tried breath meditation, my mind would get distracted, I couldn’t count the breaths, etc, and I moved on to other things.
I was also conceited, more interested in deep states, also with other topics like death contemplation, buddha / deva contemplation, you know, more fancy stuff.
But then I realised, well wait a minute. It was good enough for Buddha.
So while not completely abandoning my breath control techniques, but just being mindful of them, I started to ease into breath meditation.
Now if it’s said that breath is a hard technique to master, and perhaps my years of meditation has helped me a bit (or a lot). Perhaps. But still, my mental block had nothing to do with me experience or likewise. In fact, my “experience” hindered me because I just taught breath was something for beginners, whatever that means.
The moment “breath meditation” turned into “breath contemplation” was my breakthrough for me. And I think there’s something to this approach.
Buddhists, Jains, Hindus, Jews, Seculars, everyone pays attention to breath. Breath seems like a very mundane thing, and yet, it’s the most crucial thing. I can go without food for a week/month. I can go without water for 2-3 days. I can’t go without breath for more than 10 minutes.
So once I delved deeper into this topic, rather than just focusing on this breath, but on breath in general, then slowly but surely it became a lot easier to keep my attention focused on this breath.
So I could suggest a similar approach. Try to connect with sages of past as them “What is it about breath?”. Try to notice how your body reacts to each breath. Just think about breath if you can’t focus on your breath yet. Take the idea and run with it.
Weird things work with breath counterintuitively. For example, if you want to take a deep breath, first exhaling all the air in your lungs allows your body to take a deep breath automatically. Taking two medium-long inhales without exhaling relaxes the brain considerably. There’s some interesting techniques.
I’m not sure if commentaries go deep in various breath techniques (suttas just talk about awareness of breath as it unfolds as far as I know). But there’s a wide literature of various things you can try, from windblown musicians’ exercises to more secular therapy approached.
All in all, even your inability to focus on breath can be a topic of recollection and investigation. And from Buddhas of all ages to anyone remotely spiritual, breath’s played a crucial part. To connect with those dimensions is an amazing treasury for any serious practitioner, I would think.
Good luck!