Not sure where I found this, but I kept it.
"A veteran is someone who, at one point in his life, wrote a blank check made payable to "Canada" for an amount "up to and including my life"."
Kind of covers a broad swath, but basically means you answered the call.
Being a former reservist, I certainly don't think I am, despite the definitions by the RCL. Some folks I know sure are though.