Yes, always, every day! The odd time I toss my pants in the laundry basket and forget to swap it over I'm conscious of it all day.
I carry a spyderco dragonfly most days, but I also have a Benchmade mini barrage that comes along from time to time.
As for why; Being a loyal Canadian, self defense never crosses my mind, as we are better off letting the criminals abuse us like the sheep we are. However, I find I use it at least 4 or 5 times a week for an endless range of tasks. If you carry one on a regular basis and it's readily available (pocket clip) you will be amazed at how often you find use for it.