Paul Bradford:
Background: have only meditated about 40 hours in my life, made a resolution to sit 2 hours a day in 2013 and shortly after read MCTB
I don't understand, in practice, how to focus on concentration and developing samatha jhanas vs. just ending up doing a vipassana sit..
From what I can tell the main difference is that for samatha you focus on continuity of the breath whereas for vipassana you notice sensations as they arise, which feel discontinuous. But in practice I don't understand how to focus on continuity of the breath. I am better able to focus on continuity when I don't limit the area of concentration, and feel the breath flowing in the nostrils then down through the body to the belly. But if I just focus on the nostrils snd nowhere else, the breath becomes discontinuous, a lot of the time I feel nothing and otherwise I feel mixed sensations of the breath that are not continuous in any way. If I continue focusing only at the nostrils, I feel like I'm doing vipassana instead do to this feeling of discontinuity.
Also, is there a difference between what to do with thoughts between samatha and vipassana? In both cases I'm mindful of the thought for a short moment and then direct my attention back to the breath.
My experience has been that the two should be developed together. The spiritual faculty of concentration is used to make the mind tranquil so that you can then clearly see (vipassana) arise and pass away, which is the development of the wisdom faculty. As this process continues, wisdom allows deeper and more subtle aspects of the mind to be seen, although this requires further stilling of the mind / increased tranquility.
Also I suggest investing time exploring the breath without any expectations. See how it flows down to the belly. Especially notice how trying to maintain awareness of the breath can at times make it feel rocky because you feel as though you are unintendedly trying to control it - who is "breathing?" I mean this in the sense that any time it feels like you or some agent is pulling air down into your lungs or expelling it from the lungs, notice the sensations of feeling as though there is someone or an agent "controlling" those muscles.
Sometimes people get frustrated that they aren't somehow watching the breath the right way. A useful trick is to question why you aren't already meditating perfectly (by whatever standards of watching the breath you have). Then notice all the phenomenon that seem to block you from meditating perfectly and where / how those phenomenon seem to come from and notice how they disappear.
Hopefully you find some of this helpful!