Dave,
I come from a lively military background (army 17 years) and I also find the boredom gets to me at times, though I'm 'lucky' in that I work with Wor Lass 70% of the time.
For example, her A-Frame ladders slipped from beneath her today and she's torn a finger nail and winded herself. A few years ago she put her A Frame on a door to clean the window above and nearly killed a hefty customer who then opened the door. It's the laughs like that, that break up the day.

I'm not so good when I work alone; MP3 Players are a godsend though; so are talking books, but I only use them when I'm working alone. Talkative customers spoil it though, disturbing you by trying to pay you 'n' stuff.
My advice is to charge well and you won't have to work a long day; so you won't be getting too bored!