After a weather delay I finally got out to do W4R1 today and was surprised how well it went. The first half of the run went well, then all of a sudden I got to the end of the second 5 minute stretch and was pleasantly surprised that I was done! So far I don't ache afterwards (although I did extended my post-run stretching routine a bit just to be sure) and it's given me a huge confidence boost that I really can do this.
Looking forward to complete the rest of this week now (and pretending that I don't know how much more running I have to do in W5!).