Endurance exercises (or, aerobic exercises):
Your physically demanding occupation is similar to an endurance exercise.
You are able to speak and sing freely while doing the activity
Walking slowly, doing chores, generally doing undemanding tasks
You are able to speak with a certain ease, but you are unable to sing properly
Walking briskly, cycling, dancing, gardening, doing occupational tasks
You are unable to talk in a consistent pattern and cannot say more than a few words before catching your breath.
Running, swimming laps, jumping rope, doing very demanding occupational tasks