I lost my grandfathers when I was 15 and 20. At the time, it was sad but expected and the young, self-absorbed me didn't take too much time to grieve. That's not to say that I wasn't sad, I was. Watching my parents lose their parents was devastating and I was close with my grandpas. I was sad to think that I'd never hug them again and that they wouldn't see me graduate (one from high school, the other from college).
I've found that I haven't gotten less sad, but more sad as the years have gone on. It literally takes my breath away to think that neither of them know my kids. Bear reminds me so much of my dad's dad. They would LOVE each other. To think that they'll never play chase through the house breaks my heart. I wish I knew what nickname my mom's dad would have given the kids. All of his grand kids had ridiculous/embarrassing nicknames.