Hitchhiking in California in 1978, I met a couple from British Columbia at a campsite who were cycling south along the coast to San Diego or Mexico or... This was my first real exposure to bike touring.
The following year while in San Diego, a friend took off on a cross country bike tour: north to British Columbia, east across Canada, and south-east to New York City. Shortly after, I hitchhiked home to Toronto. A month or two later, he called to say that he would arrive in Toronto shortly. We spent several days together in Toronto, and it was then the idea took serious root. I bought my first touring bike almost immediately, and began doing day-trips. Another nineteen years passed before I did my first multi-day trip: 18 days in Alsace and Burgundy in France. Since then, I have done many longish tours in southern Ontario, Quebec, Switzerland, and Italy.