May I touch on something that hasn't been mentioned so far?
These days we shield our kids from the world: ferry them to school, vet their friends, encourage them to stay in, control when they're out - and then suddenly expect them to make mature informed decisions when they're 17/18. That's totally unreasonable. They can't do that until they've seen a bit of it first - and I don't mean on the telly or from a car window. No wonder so many
seem un-motivated at that age, they're nearly all in handcuffs and chains.
I was like the other kids of my generation. I walked over a mile to school on my own at 8, was taking the train to the next town alone at 11, standing outside engine sheds hoping to cadge a ride at 13, hitch-hiking to the coast at 15, lucky enough to go flying at 17. By 18 I was totally street-wise and able to say I'd seen enough of the world of work to know that flying was better than all the alternatives. Kids don't have the freedom to do all that now - anyway they'd be put in Care if their parents let them.
I'm not saying we were smarter than kids today, far from it, but circumstances required us to stand on our own feet much earlier and gave us the experience to do so.
This generation will get there too, it just requires a little longer. That's why university is such a good opportunity for them - to gain some independence before making career decisions. Part of that process is making mistakes, changing your mind, pulling yourself out of the hole you've just dug and gaining confidence on the way.
Unfortunately you can't do that (change your mind etc) if you've just joined the Services for x-years!
Please, think twice before encouraging your kids to sign on under the age of 20 unless they really, really know what they're about.
Age 20 now is about equivalent in experience to when you were age 17 - in the days when kids were allowed out occasionally.