I'm sure we've all heard this at some times during our running careers, but I just want to throw something new into the mix.....
Over the last few months my running has got slower and slower - sometimes I find it hard to break 10 mins per KM, (this is barely above my walking pace, and I was faster than that when I started C25K all those years ago) and harder and harder...until I reached the point I didn't want to run again, ever...so many people told me I needed to be doing speed work - well, I do one interval run per week usually, and that wasn't helping...
I tend to think of running as a barometer of my general health and mentioned how difficult exercise has become to my ENT specialist last week (Some of you will know I had part of my thyroid removed a few months ago) and he took me seriously...some of my hormone levels are not quite right, still in "normal" levels but only just. He prescribed Levothyroxine tablets.
I've only been taking them for about a week, but I've already reclaimed about 1 minute a KM - I averaged 9 mins pace yesterday on my run, you might imagine I was delighted with that!
So, my message here is sometimes it's not your fault, something else needs to be taken into consideration.