I've said it before and I'll say it again, my kids are so different.  While they may look very alike and enjoy similar things, their personalities are night and day. The things that motivate them and their determination is just at opposite ends.

Matthew is motivated by reward and by pleasing people.  He never wants to disappoint anyone and will do anything in the world if it involved achievement and reward.  He's easy that way.

Five years in and we're still trying to exactly pinpoint what motivates Ben.  He, of course, wants to do the right thing and please people, but he's not nearly as affected by it as  Matthew is.  If you tell him you're disappointed in him he will not crumble into a heap like Matthew does. He's tougher, more stoic.  He's harder to read.
And he doesn't seem to be as "into" things as Matthew is. He tends to get bored easily and once he's bored nothing seems to motivate him to perform.

A couple of years ago I enrolled the boys in soccer and Matthew enjoyed going every single week and still asks me if we can go back.  Ben, on the other hand, made it through one class and then *maybe* the first five minutes of subsequent classes, before he was sitting in the corner asking to go home.

Now we've got the kids in karate and it's going great. Or at least it was. But now suddenly Ben seems to be resisting it.  Nothing seems to change his mind. I've tried reward (new belts!), reasoning (we've paid for the classes in advance), threatening (you don't do it and you won't be allowed to play on the iPad tonight). Nothing works. When he's done, he's done.

And he seems to "be done" with things quickly. He "quit" soccer, he want to "quit" karate, he got bored with school after a few weeks and asked to stop going. None of this is the fault of the classes/school. They're great.  It's just him. Nothing seems to hold his attention.

I get so frustrated with him because I want him to follow through on things (and it's not like he's just "trying out things to see what he likes", he's always been one to lose interest with everything). And me being frustrated does not help the situation, it just leads to some bad parenting on my part.  I think where I struggle the most is that I don't want to "figure out a way to get him to do karate", but rather I wish his personality was different and that he enjoyed things for longer periods of time.  And changing my kids' personality is not something I'd really ever want to do.  So I'm stuck.

On one hand I don't want to threaten and force, but on the other hand I don't want him to constantly be a quitter.  What would you do?