Here is some great advice from my good friend and professional ventriloquist for over 60 years, Bill DeMar:
As a working ventriloquist, you should have a large lung capacity. A vent should be able to
give a lot of power to the figures voice. A vent should NOT have to take a breath in the middle of a word OR sentence.
Find out what your lung capacity is right now. You can do that simply by timing how long you can hold your breath.
Then, do a physically demanding exercise, like deep knee bends, followed by pushups, for example. Do these exercises back to back until you’re panting and out of breath. Then rest. Then do it again.
After a few weeks, test how long you can hold your breath again. I'll bet it will be longer than the first time you tried. And the longer you can hold your breath, the more lung capacity you have.
As I said last year or the year before....comedy is not whispered or mumbled, it's presented loud and bold.
Watch and listen to any cartoon show or sitcom and you can't help but notice that it's LOUD, CLEAR AND DISTINCT. PUNCH those punch lines, don't let them fade and fall on the floor like so many people that I hear.
I'll bet you Terry Fator can hold his breath longer than you can and can hold a note longer then you can and make his figure talk louder than yours.
How long can YOU hold your breath? 20 seconds? 35 seconds? 60 seconds? More?
I'm so out of shape it's not funny. I haven't done anything, and I mean anything for several years. I can only hold for 70 seconds. (on the first try)
When I was younger and did vent on a regular basis, I had the capacity to swim under water for long periods of time.