How to reach back out to someone you shadowed?

Hey guys,

I've been looking for a mentor. I need a mentor. The more I think about the importance of having someone to look up to for professional growth, and ideally personal growth as well, the more paramount of a goal it has become for me.

When talking with older people (especially those in RE, my current field), I try to look for a spark. Not the kind of spark when you're dating, but the kind of wisdom, experience, and confidence that radiates and strikes a chord with you to want to hear and learn more from this person. Might not be the right way to go about it, but perhaps I'm looking at it all wrong and should just focus on feeling out who might be interested in actually helping develop someone young/green instead.

Almost exactly one year ago to this day, I had the fortunate opportunity to shadow an MD on the Debt side of a big brokerage firm for a day. It was part of a mentoring organization he was part of. The experience was a very good one, and some of the takeaways I've carried with me to this day. Unfortunately, I didn't keep in touch, but I would like to reach out either way in the hopes he even remembers me. Maybe he doesn't respond, maybe we only exchange a couple emails, or maybe he down the road becomes a mentor, who knows.

My question is, in my email to him do I just shoot him a brief note (not sure about content yet), or should I send him something a little longer regarding how I've been, my professional update(s), and ask how things are going with him and his company? I'm aware he likely doesn't have the time to read any novels I send him, but at the same time I feel like that would be the most genuine way to go about it in the hopes of reconnecting. Any suggestions would be much appreciated!

**tl;dr Gonna send an email to an MD I shadowed once a year ago, unfortunately haven't reached out since, how should I do it? **