Barbell Bench press and dumbell pullover will expand your rib cage allowing
more space for air to get into the lungs.
Also deep breathing exercises will expand you lung capacity enabling you to
sing with ease.
I can't remember the name of a singer back in the 50's but I do know
he could bench press 400 lbs.
Also soak a hand towel in hot water and wrap
around the neck this will warm up the vocal muscles.