How did Douglas make sure that he had conquered the old terror?

To make sure that he conquered the old terror, his fear of water, he decided to go to Lake Answers Wentworth in New Hampshire. There he dived off a dock at Triggs Island and swam two miles across the lake. Even though he swam with minimum anxiety, a little doubt remained within him. Next, he dived into Warm Lake and swam across to the other shore and back. Having swum in the lake without any fear or panic attack, Douglas realised that he had finally conquered his fear.

OR

Douglas hired an instructor to overcome his fear of water. The instructor put a belt around him. A rope attached to the belt went through a pulley, then ran on an overhead cable. Thus, he was made to go back and forth across the pool, hour after hour. Then, he taught him to put his face under water and exhale. He taught him to raise his nose and inhale. He taught him all the techniques of swimming in water. In this way, he built a swimmer out of Douglas.