I grab our 45 lb pup to put him in the truck since he can't jump and I don't want him to by taking one arm around the front, one arm around the back legs. His 4 legs are on the inside of my arms. Pull him into your chest.
Make sense? I picked up our aging girl 65 lbs the same way when running her back and forth to the vet before she passed. Lift with your legs, not your back. Looking up toward the sky helps keep your back straight.
You are effectively supporting the butt on one arm and the chest on the other.