Sorry for not being on here much this past week everyone. Work, family, training etc...............
Anyhow, will read back but a quick answer for Jen. The most important thing isto be able to finish any interval session! Therefore, being a little conservative at first won't hurt - you can always run the last couple harder if you feel up to it. The idea is that you gradually get more tired. My experience is the first one or two feel quite hard and then the middle ones a bit easier and then gradually get harder as you naturally tire.
I would start off with running them at maybe your perceived 10k to half marathon time. If for instance you think you are a 9mm half marathon person and a 8:30 10k runner you would ideally run 4 x 1 mile at somewhere between the two.
As I said, I would run the first one at the slower end of that and go from there. Just amend as per your actual pace. Try to run the middle two closer to 10k but not so you are dying and then you can play with the last one depending how you feel.
I hope this helps. If you have an idea of your steady pace PM me or FB and I'll look at what I think you should run them at.
Intervals feel like the devils work, at first, but once you get used to them they are really enjoyable. I think Malcs will testify that they are one of the best ways to improve!
I had forgotten how much I like running on the trails through the woods behind my house. I did 5.21 hilly miles in 38:55 including a brisk 4 in the middle in 29:23. That rather surprised me considering the terrain.
I think I benefitted from running in lightweight XC spikes because it was wet, and running half of it with someone I'd never met who just happened to be in the same place. He was fitter than me and training for an ironman!
Rachel - nice going! Always good to get back in the saddle. Never run at any sort of altitude - well, other than the top of the north Downs!