Clemens, thinking he could do better than the Twins, enrolled at San Jacinto Junior College instead and set about building the body he would need to reach his goals. At age 18 he was six-foot two and 220 pounds, and not in good enough shape to achieve the velocity he needed to be truly competitive. Clemens put himself on a rigorous conditioning and weight training program and lost fifteen pounds. The conditioning program did the trick, pushing the velocity on his fastball from eighty-six miles per hour to the ninety plus miles per hour he would need to succeed in the pros.
He played well enough as a freshman (with a 9-2 won-loss record) for the New York Mets to pick him in round twelve of the 1981 draft with a $30,000 signing bonus. Just as he was considering the New York deal, the University of Texas finally came through with its scholarship offer to Clemens. Clemens, who was close to signing with the Mets, decided that playing with the powerhouse Longhorns was the better strategy. There he would have several more years to develop fully under the tutelage of Longhorns' legendary pitching guru, coach Cliff Gustafson.
Choosing the Longhorns turned out to be the winning strategy. In his first two years for the Longhorns, Clemens won twenty-five games, and lost just seven, striking out 241 batters in 275 innings, while walking just fifty-six. In June of 1983, he was the winning pitcher in the final game of the College World Series, giving Texas the national college title.
"He was an excellent pitcher in college, improving every year," college and pro teammate Spike Owen told Sports Illustrated. "But I don't think anybody could have looked at him then and known what was in store."