Michael Jordan's career can be split into two eras from a physical perspective. The version of Jordan that won six championships with the Chicago Bulls, which most are familiar with, was bulky and relied heavily on his strength to dominate in the post. But it took him years to reach that point. The Jordan that entered the NBA was skinny, graceful and so overwhelmingly athletic that he hardly needed any muscle ... at least at first. 

That changed when he ran into the Detroit Pistons. The so-called "Bad Boys" developed a personalized strategy for defending Chicago's MVP known as "The Jordan Rules," and while it was far more complex than it gets credit for, its central tenet was to play Jordan as physically as possible. For three consecutive springs, the Pistons bullied the Bulls out of the postseason. By 1990, Jordan had had enough. 

"I was getting brutally beaten up," Jordan explained in episode four of "The Last Dance." "And I wanted to administer pain. I wanted to start fighting back." 

While Jordan's commitment was unquestioned, it took a stroke of luck for him to find the program he'd need to transform his body. After Chicago's third straight postseason loss to the Pistons, fitness trainer Tim Grover reached out to the Bulls with an offer to help, according to Bleacher Report's Ric Bucher. Jordan agreed to a 30-day trial that ultimately never ended. Grover is now revered as one of the greatest trainers in NBA history, but at that point, he had to rebuild Jordan from the ground up. 

"He wanted to start a strength and conditioning program, but he was afraid of lifting weights, because he wasn't sure what the effect on his game would be," Grover said according to Stack. Jordan's reluctance was justifiable given the success his leaner body had granted him, but the Pistons forced his hand. He had to start lifting weights consistently for the first time in his career. Over time, he managed to put on a substantial amount of muscle mass. 

"We started at 200 [pounds]," Grover recalled in "The Last Dance." "We added five pounds until he got to 215." 

Jordan's work ethic allowed him to put on that weight despite the calories he was burning on the floor. 

"I would give him a certain amount of reps to do, but he would never stop at that number," Grover said. "If I asked for six, I knew he was gonna do 12."

The results were nearly instantaneous. Jordan went 7-2 against the Pistons in the regular and postseason combined. He averaged nearly 32 points per game in those five regular-season matchups along with almost 30 in a four-game Eastern Conference finals sweep. The Bulls went on to win the championship against the Los Angeles Lakers in the next round. 

Even with the Pistons in the rear-view mirror, Jordan recognized the need to continue lifting weights. The 1990s were littered with copycats, most notably Pat Riley's teams in New York and Miami. He took things to another level while playing baseball in 1994, adding even more weight that would ultimately define his playing style during Chicago's second three-peat. 

While Jordan's dunks draw the majority of his highlights, his final years were defined by his post play. The player that was once pushed around by the Pistons eventually dominated a generation of big men in their own domain. That was only made possible by the work that Jordan did with Grover. Like all great nemeses, the Pistons pulled the best out of Jordan and helped turn him into the player he was destined to be.