If they are passionate about it it is a fun and rewarding career, with lot's of job opportunities.
They won't get outside much, they will need to stay active after work to not get fat, and that programmer != sys admin.
I'd especially tell them what it ISN'T. There are a lot of misconceptions about what computer science actually is and a lot of is perpetrated by well-meaning adults who tell kids "go learn about technology" and glom computer science into that extremely broad category of "tech".
I work for a youth organization, and I always have kids watching what I do and going "Cool, can you teach me how to hack?" Invariably, they get disappointed when I show them how to ssh into a remote machine and recompile the kernel instead of breaking into a DoD mainframe and launch missiles at China or something. And anytime I do try and generate interest in actual programming, it is hard to get past the "How do you program games?" point. Let's work past printf and scanf first, junior.
It's a toughie. IANACS, but I've taken programming and numerical theory classes and it can be tedious and detail oriented. It's hard to put that up against a generation who has a lot of instant gratification when it comes to their experience with anything technology related.