Sentence 1: Luis' personal trainer always made him stretch before every workout. 
 Sentence 3: So the day he found his trainer was absent, he saw an opportunity 
 Sentence 4:  He jumped straight into his squats without stretching or warming up 
 Sentence 5:  Both thighs strained, now he understands the importance of stretching 
 Given Sentence 2: He hated the ritual though, feeling it was tedious and unnecessary.