There were three impetuses for me:
1. I was 21-years-old in 1977, and a friend told me the story of how she had bicycled in Holland. I couldn't get the image out of my head...
2. A year later, I hitchhiked across Canada and south to California. At a campground in California I chatted with a couple from British Columbia who were cycling down the coast. Until that moment it had never really occurred to me to actually do it myself...
3. A few months later, I watched a friend set off from San Diego on an extended cross-continent tour. This was the first time that I had witnessed someone I knew touring. Several months later, I arrived back in Toronto just in time for my friend to cycle into town. He told me amazing stories of his travels, and I was excited and jealous at the same time.
I bought a touring bike a few months later. Although I did plenty of day trips, it took me 19 years to actually do my first multi-day tour! Now as a 51-year-old with a family, I still manage one trip lasting seven to eighteen days every year or so.