Behave - that's just the sort of arrsehole attitude that makes young recruits UFS... give the little bastrads some danger and excitement, if they're too scared to put on camo at the age of 8 then they're hardly suitable anyway.
Encourage the fit and the healthy, show them that Service life is something they should aspire too and to be proud of. The money-grabbing, work-shy chavs can fcuk off and find their own level in the food chain.
Let's not dumb it down, give them inspiration through competition. All may apply, but not all will be selected type programmes. If you're good enough come and try British bulldogs, touch rugby and standing-still-for-hours-on-end-without-flinching type games... Weed em out, rather than allow the weeds in.