How do you motivate a young NCO to practice "Service Before Self"?

Lead by example, and don't say or SHOW otherwise.

"We need to finish this task... but screw it, lets go home, nobody will know if we finish tomorrow"

"man I hate doing this crap...id rather be at home watching the game...but you know the CDR is going to check up on us...so lets finish , because we will get caught"

Vice

"We need to finish this tonight, the crew is counting on us...Get going, I'll ask if we can have a late call in the morning"

"Look guys, I know this detail sucks, sweeping the MP line ain't saving any lives....but its the job, so lets do it right, as best we can, and have the place ready for final formation"

Hold that person accountable for their actions, if they're doing good tell it same with doing bad. You need to councile and teach good behavior so they understand what's right. If they aren't getting it bad evals and reduction in pay grade could be their consequences.

Hi, TSgt Fabian.

You lead from the front, and present yourself as the NCO others want to emulate. When they see that you are consistently first in and last out, that you always put mission first, that a true leader is the servant of his subordinates, they'll get it. You motivate by example.