When shooting with kids I know that the joy ends when they are ready to be done.
They also enjoy reactive targets far more than shooting at paper. It does not need to be fancy. It can be charcoal briquettes, eggs, empty shotgun shells, those cheap plastic soldiers.
If they are shooting at paper, having some kind of "story" makes it more fun. A hostage or terrorist scenario, for instance.
Also, too much gun. And poor hearing protection. And crappy eye protection. Those take the fun out RIGHT NOW.
Targets that are too small. Maximum motivation seems to occur when about half the shots are "hits". Too hard steals the joy much more quickly than too easy. So tune the target size so "hits" are between 65% and 95%. Once they get to 95%, consider making it more challenging.
From the campfire
1. Living where there isn't quick and easy access to a place to shoot.
2. Shooting something that kicks so much it isn't fun to shoot.
3. Having rifles that are just too expensive to shoot, due to costly brass, boutique bullets or using half a can of powder per shot.
4. Trading rifles too much- Trading away guns that are fun to shoot just because you have the urge to trade, and ending up with a gun that isn't as good as the one you traded away.
5. Not trading rifles when you should-Keeping something in the gun safe that you never shoot and that has no sentimental value and is not an investment- Maybe it would be better to go trade that for something you would shoot, be it an air rifle, muzzleloader, BAR or even a shotgun, as much as I hate those things.
6. Just focusing on one kind of shooting- It's easy to get wrapped up in shooting groups, because rifles are so accurate these days, but there's lots of other fun stuff- shooting ground squirrels, plinking clay birds off hand, shooting a handgun for a change, trying some kind of competition, formal or not.
7. Not having a shooting partner- A shooting partner will get you out more often and offer some good advice, perhaps. Also, consolation on bad days and congradulations on good days is not a bad thing.
8. A very general concept- Getting to caught up in the minutia of shooting- Trying to wring the last 10 fps out of a load, or measuring groups to the 1/1000 of an inch.