I vote in municipal, provincial, and federal elections, and whatever plebiscites or referendums come along. I even took advantage of the open invitation the federal Liberals extended to everyone to vote in their last leadership race, whether they were a party member or not.
I've sent letters, signed petitions, participated in rallies and protest marches, and used to work for Elections Canada, back in the '80s and '90s.
Voting is something I've always considered important. It was one of those Mysterious Things that grownups got to do that kids couldn't, and I remember my grandparents taking me with them to a little one-room country schoolhouse where they would vote... and I wasn't allowed inside with them. Rules have loosened considerably now, as people bring their kids and even their pets to the polling stations. I'm not happy about kids accompanying parents behind the screen at the voting stations, though. Babies are one thing, but kids old enough to read is something that technically violates the whole "secret ballot" thing.
Most Canadian kids get excited about their 18th birthdays because it means they can legally drink. I couldn't care less about that. For me, my 18th birthday meant being old enough to vote (I'd actually felt ready for that since I was 16, which is one reason why I support the people who want to lower the voting age to 16). I see it as my duty as a citizen, and there is some validity to the idea that if you don't vote, then don't complain about how things turn out.