The hard part of introducing the System to your team for the first time is always going to be the first few weeks of practice.
I've been exhausted after each of our first two workouts, and any teacher understands what I mean. When you are in front of a group for an extended period of time, and actively teaching a new concept or skill, you find yourself drained at the end of the lesson/school day. (Frankly, I don't know how you high school coaches do it, teaching all day and then having any energy left for basketball practice!)
Now, technically the System ought to be "easy" to teach compared to conventional basketball, because it's fun and relies more on effort and a clear, simple structure rather than on lots of drillwork and precise execution. I've used the analogy in the past that ball-control basketball is like a chess match, where every move takes time and--after half an hour of intense concentration--you capture a pawn. But System basketball is like taking a sledge hammer and smashing the chess board to bits. Not real complicated, but very aggressive, very effective, and very demoralizing to one's opponent. (The downside comes when you call up that chess opponent to reschedule a match for next year... not a lot of takers!)
So, given how fun and simple it is to take the sledge hammer approach to basketball, practices shouldn't be that emotionally draining, right? Yet they are for me this year, and I think there are two reasons for this. First, I teach too many breakdown drills initially. I've seen other System coaches who adhere to Coach A's approach of just warming up, shooting 100 threes, and then jumping into "6 Line Shooting" (a drill that teaches players how to execute System end-of-break options using three lines on each end of the floor: handler, screener, and shooter). Next comes 5/0 and 5/5 situations, followed by a shooting contest at the end, then it's Miller time. On and off in one hour and fifteen minutes!
I'm not sure if my tendency to drill more has to do with a) my situation coaching female players (my gut and 35 years of experience says they benefit from more skill-work), or b) my need to micromanage practices, and my use of breakdown drills to express that compulsion. I honestly think it's "a)" but am willing to seek counseling if I'm wrong about this.
The second reason practices are wearing me out this year (poor me...think about how tired the players must be!) is that every single drill is brand new to the players. After the first few System years at ONU I just called out, "Carolina Break drill!" and the players knew what to do. We required freshmen to get in the back of the line and watch, and seniors to be in the front because they knew our expectations. Players coached each other, and that makes a LOT of difference. But when introducing a brand new system, with new concepts, attitudes, tempo, and drills, it all has to come from you, at least initially. The System is not designed to be "coach centered. " But at least for awhile--when introducing it in the beginning--it has to be.
But it is worth the effort to do it right, and to set the bar high from the very beginning. After the first few weeks, you'll have introduced the offense and the press. From there on out, just polish and try to get a little better every day.
Then, watch and wait for "the light bulb to go on." That's when the Run and Gun System starts to run itself. Then you'll know that the Hard Part is over.