It felt really good. I have found a comfortable pace thanks to my shiny new Forerunner keeping me from overdoing it! It's been really useful as I now know a good heart rate for me to be working at in order to keep going without wanting to stop (that's not to say it's easy but definitely achievable :))
Actually rather looking forward to seeing how I fare on W5R3 as that is the point where it gets serious I withhold the right to take that back though hehe