I've noticed that, as non-ideal as my job is, I am a lot less cranky than I feel like I "should" be when I get home. Part of that is that I'm (by choice) not working full-time. But I think that, weird as it sounds, a very big part of the reason why I don't come home cranky and miserable is -- you guessed it -- because I ride my bike to work.
See, for around a year when I lived in Pittsburgh, I used to have a walking commute. It was approximately the same amount of time as my current bike commute (20 minutes each way). And I didn't come home cranky then, either. I really liked that job, which could be part of it... but when I moved and had to start taking the bus to work every day, I started getting cranky. And pretty much didn't stop being cranky about my job for the next few years.
I can't really get much thinking done on a bus. Oh, sure, I got a lot of reading done. But deep thinking, the kind I need to cleanse my introvert brain after a long day of working in an extravert's world... no. Not with all the stop calls, the babble of voices, people pushing and bumping into me, and oh god, the motion sickness. I don't get carsick as easily on a bus as I do in a car, but it's still present. (Well, someone's a delicate butterfly.) And I think all these various bus annoyances had a lot to do with why my attitude went downhill all those years.
Maybe there's no correlation. Or only a very weak correlation. I'm not a scientist.
I kind of wish my commute was longer, although I'm sure I won't feel that way after the first snow.