Luke knew it was going to be the sort of question he got asked a lot. Add in the fact that he hadn't been training for long there would be the surprise too. So many people expected him to have been learning from such a young age. It left a lot of questions about why he had started training so late and about the Empire. Still, it was something he probably should talk about at some point.
"Four years but it has been on and off during that time due to other events. It's kind of a long story I'd be happy to tell it at some point. I have a feeling I'm going to be telling it a lot," Luke shrugged. "That's interesting, I always struggled with the meditation part. Master Yoda always got on my back about it. Said I was too impulsive which honestly, I am when it comes to it." Luke knew himself well enough to know that. Yes he'd come a long way from when he lived on Tatooine but he still had a long way to go.
Luke took the offered crystal and frowned slightly. "It hums somewhat?" he said after a moments consideration.