The organization and in particular Pat Riley demand it and sell it. From Kennedy's article:
Riley has made this promise to other free agents over the years, and he has an iPad full of before-and-after pictures that serve as success stories to back up his claim. When a player joins the Heat, it doesn’t take them long to realize that this organization does things differently.
Prior to joining the Heat, Waiters thought he was already in excellent shape after playing four years in the NBA. James Johnson, who had been in the NBA for seven seasons and can literally kick the rim on a regulation hoop, thought the same thing prior to signing with Miami last offseason.
Most players have this reaction. Then, they show up for the team’s workouts.
“After one week, my body [was] shot,” Waiters recalled. “I was damn near throwing up in trash cans like in the movies.”
The Heat’s offseason workouts, training camps and practices are the stuff of legend. Players work extremely hard, spending a ton of time on conditioning and weight training. And it never really lets up. This year’s team was still doing full-contact practices in the final week of this season – even when a playoff berth was a realistic possibility.
Miami has a rule that players can’t put their hands on their knees for a breather during a practice or game. Any player who does this is fined $100, according to a league source who’s close with several former Heat players.
“This culture is real,” Jame Johnson said. “We have the kind of practices where you can’t go out and hang out all night and think you’re going to be able to come to practice and really go hard because I’ll call you out, everybody on this team will call you out. We won’t leave it to the coaches to call you out. We take care of that ourselves.”
“Miami is an organization that isn’t for everybody,” an agent said. “Either you buy in and you’re part of the Heat culture, or you’re not. They go after players who want to work and put in the necessary time to get better. They look for those kind of guys – the ones who have good character and want to work. They go extremely hard. They like to lift heavy and run a lot. Their strength-and-conditioning program is an emphasis. They like for guys to report early – usually about six weeks early – so that guys can focus on weightlifting and their agility and getting quicker. They’ve been doing it for a long time and they take it very seriously. Some other teams will let guys go work out on their own and do whatever they want, but Miami isn’t like other teams. It’s very organized in Miami; guys have a strict schedule, they’re working with the strength-and-conditioning team and they go hard. They will push you to the limit. After they’re done, the players exhausted because of how hard they go.”