Heh, I've actually been doing TFNA for about two months now. Just finished the "transition period."

If you're having these days where your heart rate is elevated for weeks after, during your transition period, you either started off with way too much work or you're not tracking your work honestly. In just a month or two during the base period you will wind up doing more than double what you're doing right now, so it's very important that what you're doing right now is really quite easy to sustain. Also, heart rate zones! Make sure you are following them!

About once a month I take a weekend to go to my absolute physical limits, and then take a half week or so of rest. It's probably not healthy, and it's certainly not good training, but it sure is fun. Not many people get to say they've seen the enchantments or deep into the goat rocks wilderness in the dead of winter.