I love everyone's descriptions of how their passion developed. I think for me gardening was more of a gradually growing interest that took off running when we bought our first house.
As a child my sister and I each had our own large barrels we got to plant with annuals and each had a little raised bed each that we got to plant with edibles. Tending to our gardens was our responsibility, and I think I liked the sense of purpose it gave me. We were also paid a penny per dandelion we picked so I guess I've been weeding gardens for as long as I can remember. I also used to collect insects and create little habitats for them out of shoe boxes with windows made from saran wrap. The poor things always died, but I think it built a level of respect in me towards my garden visitors.
It's interesting because my sister had the same experiences growing up, but she ended up with a black thumb and absolutely no interest in gardening. In high school my husband (then boyfriend) gave me a little lucky bamboo plant that sparked my interest in indoor gardening and lead to my dorm room and then first apartment looking a bit like jungles. We bought our first house 2 years ago this July and my interest just seemed to explode. As others have mentioned I spend hours upon hours out pulling weeds, planting, making plans every weekend during the growing season. Last year I grew my first plants from seed and this year is my first year growing veggies. There's so much to learn and I feel myself growing right along with the plants I tend to. It's something that just feels natural to me and I feel at home in my garden. It's a good thing I do have such a large space to work with outside because our house has finally recovered from tropical plant overload as my interest has spilled into the great outdoors.
At first my interest was solely based on creating beauty. Then it progressed into an interest in function and the ecological impact of what I was planting, focusing a bit more on planting beautiful natives and plants that will benefit local wildlife. Now I'm starting to like the idea of providing food for myself (and friends/family/neighbors if I have enough success) in planting edibles. I really do love it