Question

how the trainer make douglus a swimmer

Answer 1

Firstly, the instructor put a belt around Douglas, which was attached to a rope that went through a pulley that ran on an overhead cable. The instructor used to hold on to the rope and they went back & forth for weeks on a stretch.

Then once the tension of drowning began to slowly disappear for Douglas, which was around three months later, the instructor taught him to put his face under the water and exhale, and then to raise his nose and inhale.

The next thing he did was to hold Douglas by the side of the pool and had him kick with his legs.

In such a manner, 'piece by piece', the instructor built, perfected & integrated to build a swimmer out of Douglas.
Hope it helps! ^^