I enjoy conversations about virtually anything intellectual, but I find little value in questions that lack the potential to spark intelligent conversation (though there may be value in the answers to these questions). I tend to focus on areas in which I disagree with other interlocutors; my brother once said he had "never seen a better living personage of devil's advocate."
I prefer one on one interaction to conversing in a group. When talking to multiple people I'll often think of something pithy on a topic right after the group moves onto another topic, so it's harder to discuss an issue in depth. I prefer listening to talking. I'm more interested in refining my opinions than in changing those of others.
I have Chronic Fatigue Syndrome. Over the past three years, at worst I've been unable to walk more than 75 meters or go up more than two flights of stairs without resting. When I'm feeling bad my mental acuity also takes a major hit, making me I absent-minded and unable to do anything that requires much concentration, such as driving, playing chess without hanging a piece every other game, or reading physics. At best, I can walk two kilometers and don't have any mental problems.