Joining the Reserves from PS.

Hi all, I’ve been a public servant for the past few years and I think I might want to join the armed forces as a reservist considering the current political and global climate (If they'll have me, I’m no spring chicken and ‘out of shape’ is a bit of an understatement). I understand it's mostly a week end commitment but also a month long span as well. Is there a way to do this, I know there are quite a few considerations the other way around, from CAF to PS, is there some sort of consideration if I want to do this. LWOP, or half pay or something? Officer training? Some sort of specialized recruitment office? Anything really…. Thanks in advance.