Deb,

Thanks so much for you reply - it's so good to hear that someone else can relate to my love-hate thing with running!
You're so right about setting small goals, that's really what I need to do, rather than growing despondent with the (seemingly) lack of improvement in my performance (although structured training would do wonders in my case, I'm sure!).
The article you mention seems a really good one, with sensible advice that I can relate to.
In terms of heart rate, my supposed maximum heart rate is 183 for my age (38), and typically it usually hits 184 when I'm at my maximum effort (ie 10 on a 1-10 scale), but I've managed to push it to 191 before now, albeit unwittingly - both on the bike and running - so logic tells me that 191 is actually my max (I was just short of throwing up!).

Your advice has really inspired me to structure my programme, with sets of achievable targets (and maybe bigger goals, like 10km races further down the line) and to focus on time and a manageable/realistic pace. It's always easier to see the bigger picture when you know that what you're doing can bring improvements, as it has with you.

Again - thanks for the input, it's been really helpful. Hopefully I'll be reporting that things are progressing over the next few weeks!