Well, I ain't perfect at it, but I think DHV's pretty easy - just do lots of cool stuff and be really excited about it.
Counter example:
(In a flat, bored, boring voice) "Yeah, I'm a karate black belt, but that's not very interesting"
Versus:
"Yeah, I've been doing Karate for years, I just fell in love with it so much when I started and wow it was hard but I love how you can see yourself progressing. All the kicks and strikes and jumps you see the black belts do when you start and you think "I could never do that", well, after a few years you suddenly realise you can, and then you realise that maybe the stuff that still looks impossible give it a couple more years and you can do it, and yeah, now I can, and I'm teaching it a bit now, which is great - you see little kids and it all strikes them in exactly the same way. "I can never do this... oh shit, I can!""
Which probably leads her into "oh wow you're teaching it now" and then you can mention that you're 1st dan or whatever, and she'll ask what that means, and you can talk about black belts and you've got the DHV in without it even seeming like you were trying - you just got carried away because you love it so much!
Wow, now I'm all amped after having typed that
P.