If you're playing blues, one of the reasons second position (which is playing a blues in A on a D harp) is good is that it lets you control your breathing well. You have to learn to work in blow chords with all your drawn notes so you can breathe. This is vital: being able to work your breathing into the rhythm so the whole thing is seamless and so that you are simultaneously providing a rhythm backing and breathing. If you are consciously trying to breathe (or consciously trying to do a rhythm backing) it will sound forced and unnatural.