The boy's was half empty in a few gulps.
He managed to keep his body fluids up by frequent gulps to replenish his rapidly diminishing energy.
If you take big gulps of air there is no problem; with shallow breaths there is a hint of flutter.
You need to take it in small sips rather than huge gulps in one go.
The is proven to be the most beneficial way to take liquid on board rather than large gulps.