My experience of the past several weeks is that travel is really bad for a training program. I was in a great groove up to mid-March, but travel since then to Houston, Bermuda, and Stockholm really knocked me back a bit in spite of one or two good runs since then. The good news is I've only got one more trip coming up - Munich for two days next week - and then things look pretty clear.
One way I've been out of a groove is that my knees have been bothering me a lot; I've also felt dead-legged. I'm not sure if that's a function of an irregular training schedule, overtraining (there was that 15 mile run in Houston....), bad eating (way too many buffet meals), old age, or maybe all of the above.
Over the past week I've treid to adjust by backing off the miles and the pace just a bit and by doing a lot more stretching (mostly by using a roller that looks like this); it's a great tool for stretching out your leg muscles.
The good news is that today's run was the first one in a while that felt pretty good, and I felt good afterwards. I ran three loops of the reservoir in Central Park at about an 8:40 pace; with the trip to the park and back, the run in total was about 6 miles. I'm hoping to run again tomorrow, so we'll see how that goes.