I've consciously chosen singleness as a permanent way of life. My brother's chosen it for the last 4 years and whilst he hasn't made any formal commitment to it as I have, he says he'll look for another relationship "when he's ready" and he isn't ready yet!
I find myself in comparison to many people I know who are always in relationships, much more sure of who I am, what I want, what I'm doing etc, and more in control of my life. Obviously I'm not saying relationships are a bad thing because I can clearly see that for a lot of people they're brilliant.
I don't feel at all lonely... I've written at length about my choice for celibacy on my website