It's got me thinking, though. I started out with only a 50mm lens and I was happy. I concentrated on the content and I learned to know my lens really well. Of course, there were time I wished I could go wider or longer, but only seldomly.
For people without many lenses, they may think that's a good problem to have. But sometimes it does feel a little like distraction. I have these lenses: 28, 35, 50, 90. I slap on the 35'Cron when I'm going with a single lens during the day, and 50'Lux at night. If I'm carry a bag, then it's the 28-50-90 lineup.
Many have said similarly: "Limitation, in Art, breeds creativity." They argue that using one single focal length for force you to be more creative in capturing a scene it may not be perfect for. Maybe, you'd have to lie on the ground to capture the tree in full, or something like that. It's all true. But I'd say: I do shoot with one single lens, an image at a time ;-) It's all about self discipline. If I'm going out with 3 lenses, I simply choose to start what I think is the best lens for the situation, then only change lens when necessary or location changes. Self-imposed limitation, I guess.