In addition to what
@halocline says, jumprope and jumping jacks are two specific exercises for breathing
less heavy while making more energy. And all of oriental martial arts are based on breathing. And then of course there's levels of fitness where they train at altitude to condition themselves to make more energy from less O2.
Whether your more efficient O2 use automatically translates to lower breathing rate on scuba may be another question, but by and large it seems to.
I was once on a boat with a lady who surfaced from every dive with 1000+ psi instead of everyone else's 500-800 (boat logged end pressures). Some people just have gills.