When the breath energy is pleasant, allow the sense of pleasure to permeate through the body. Focus primary attention on the sensation of comfort that you’re gaining here right now, because it’s a blameless comfort; it’s a blameless pleasure.
"When the breath energy is pleasant, allow the sense of pleasure to permeate through the body, so that no part of the body is untouched by that sense of well-being. There may be little pains here and there, but don’t pay them attention. Focus primary attention on the sensation of comfort that you’re gaining here right now, because it’s a blameless comfort; it’s a blameless pleasure. Again, that’s something that makes the path noble." ~ Thanissaro Bhikkhu "Noble & True"