Well, I'm not airline pilot (yet

), but I can tell you that in order to keep myself focused, concentrated and sharp, it often isn't fun when I'm flying because I'm very intent on what I'm doing, and I have every intention of doing things the best and safest way possible. My (ex) CFI, Zack, immediately saw this in me-it's not often you find this developed so early in a 15 year old GA pilot (many GA pilots are simply unsafe). Every time I see him (lol he still practically runs the airfield even though he now has a job elsewhere), he never forgets to mention what a great pilot I'm going to make.
For example-The last flight I took, my new CFI, Matti, took control of the airplane during taxi abruptly, pointed it towards a couple of other people, and exercised the throttle, revving it. While it was funny (he was a safe distance away), I had my eyes on the taxiway, getting ready to take back control of the plane and watching for traffic coming our way. After our flight, I walked into the terminal building to see Zack there-I was like "hey, when did you get here?" He just looked at me and said "what, are you blind? didn't you see me? I was the one Matti was doing the engine thing to". Naturally, I explained why I hadn't seen him and got the obligatory "you're gonna make a great pilot..."
In general, I am too concentrated on whatever I'm doing to truly enjoy it, which is why I enjoy my cross countries. When you're flying locally, you always have something to do. Not so when you're cruising for 45 minutes. Now thats fun.