VANCOUVER - There are a few constants in William Shatner's career: he will always be working, he will always be mocked - not least by himself - and he will always be James T. Kirk, captain of the Starship Enterprise.

Those are the reasons why Shatner is appearing this weekend at Vancouver Fan Expo, a three-day gathering at the city's convention centre for fans of comics, sci-fi, horror, anime, gaming and the people who make that pop culture.

It's one of “two or three - very few” such shows Shatner said he chooses to attend in a year.

Shatner said in telephone interview from Los Angeles that he continues to attend the events because he encounters constant reminders of the relevance of “Star Trek.”

In a recent example, his driver suddenly stopped on the way to the airport to tell Shatner about being tortured as a prisoner of war.

“The only way he kept alive was remembering words that I had said in the part of Captain Kirk,” he said.

The series originally ran for three seasons from 1966 to 1969 before NBC cancelled it because of low ratings.

It became a cult classic in the 1970s because of constant syndication reruns, which led to movies, beginning with “Star Trek: The Motion Picture” in 1979.

Those reruns also provided comedians with fodder for mocking impressions of Shatner as Kirk, often so exaggerated that he didn't recognize himself.

“I'd have to say, 'Who are they doing?' in the beginning. Now I realize they're doing me, so I can put that on and play with that,” he said. “But what seems to have happened is everybody's grasped the idea that I'm trying my best.”

He said some of his performing quirks, including his stilted dialogue as the captain, came from memorizing pages and pages of lines.

Experiences like that and his encounter with the driver are the basis for an autobiographical one-man show, “Shatner's World,” that toured Australia and Canada in 2011.

Touring Canada renewed the Montreal native's appreciation for the country, he said.

“I've been from one end of the country to the other in the last couple of years in a way that not many people do, except for soap salesmen,” he said. “And I've seen Canada in all its fresh, glorious beauty.”

“Shatner's World” ran on Broadway in 2012 and he continues performing the show.

“It became a show that had as its thrust the desire to work and say Yes to opportunities either professionally or personally and the concept of grasping life and making it work for you as best you can in the limited time we have.”

At 84, Shatner continues to say Yes, including recently completing four episodes on the supernatural series “Haven.”

“I just finished a show in Halifax in which I had many, many long speeches,” he said. “I thought, 'This is going to be an interesting test to see what my memory's like.' I had no problems whatsoever.”

He described his health as “superb.”

Shatner said in the past weekend, he had ridden five American Saddlebred horses - he raises the animals - competing against a field of a hundred that included 18-year-old riders and came away with nine blue ribbons.

“Why in God's name would you retire when I feel like I'm just discovering how to do it all?”