When I listen to the Spring Forest music , it compliments the exercise. Sometimes the natural sounds outdoors are a nice change, although it is hard to avoid some noise produced by civilization. Silence is also good. Classical music may be ok, but I would think certain passages could be a distraction and take you out of focus. I often wear a headset and clip the player to my waist, and go outside with the SF tape. It nicely shuts out the sound, but I still get the fresh air, a nice breeze here and there, etc. It feels much more open having the sky as opposed to the ceiling.
Mike, I noticed your posts are late at night.
I am not sure how the time zones work in this forum, but make sure you get plenty of rest. If you are ill, going to bed by 10pm/11pm is better. Exercise, for me, early in the morning is great. The time seems to go much faster. It is easy to get into the exercise.
When the birds start singing, there is new energy of the day to experience.