| Steve,
good to hear you're touring! that's great. I'm going to be doing the same thing Through Europe and Asia in June and July.
It does get tough sometimes keeping it all together, and there are a few things that help me to keep enthusiasm when I'm on a long tour.
I work out a whole lot, and stay in good physical shape so that my body can endure slightly less sleep, or slightly more uncomfortable journey's. when I'm on the road I'll make sure I get to the gym at least four times a week. I take a jump rope with me everywhere, and have a work out routine I can do pretty much anywhere without a gym. So keeping the body fresh keeps the mind fresh and stimulated.
The way my mind works, and it's not the same for everyone, is that i'm happy when I'm playing and working. I tend not to have to do tours I don't want to these days which is a nice luxury, but I'm also very capable of being happy no matter what I'm playing. I'm constantly searching for new ideas musically so it doesn't matter if I'm home in NYC or in a van in latvia, I'm still thinking. I take manuscript paper with me wherever I go to document ideas, and record tons of ideas into my cell phone that has a little recorder on it. I try and play tennis wherever I can fit my rackets in on tour, and where I know there will be courts. I try to prcatice every day when I'm on tour too, even if it's silently in the van, or in an airport lounge, or even on the plane sometimes if it's not too crowded and I'm on a long haul flight. I also have my laptop and studio with me pretty much wherever I go so I'm always working on arrangements, productions, and composition.
I also don't do any drugs of any kind, and drink very mildly when I'm on tour. There are nights where it gets out of hand sometimes, but 98% of the time I'm looking after my body, and making sure I'm fit enough to be on the tour I'm on. And I also know that when you beat your body up with drink and too much crappy food, you feel like arse when you get home after a tour. I never want to feel like that ever again, so I make a huge effort to take it easy on tour.
There are sometimes though when it's just exhausting. When two gigs are back to back and are 15hrs drive from each other. but hey, that's just the way it is sometimes. And you have to pay a lot of dues doing stuff like that to get to the point where you don't have to. And even still then, the nature of being a musician and touring means that sometimes you will come across crazy schedules no matter who you are.
And to your question about keeping alert when playing dempanding music such as jazz:
firstly I don't think of any gig as being differently demanding. I try and dedicate myself to every note I play no matter what the style is. I personally think that jazz keeps me more alert than any music I play because my mind opens up improvisationaly and makes me think about tons of different things all the time.
easy,
Janek | 
