Sentence 1: Billy was very afraid of being in water. 
 Sentence 3: He mustered the courage to attend a morning swim class 
 Sentence 4:  He was happy that the instructor was so nice and supportive 
 Sentence 5:  Billy learned to swim that day and has enjoyed it ever since 
 Option 1: One day, his father advised him and boost him to learn to swim. 
 Option 2: One day he decided that he would overcome that fear and learn to swim.