Evening all, Firstly, yes I'm orf to see the ol' doctor next week regarding this issue. Basically posting here to see if anyone else has experienced this. Basically, I feel as unfit right now as I have ever been. In fact, I jolly well am as unfit as I've ever been. The strange thing is, that this is neither due to under or over-training. (Or at least, it surely can't be. I'm not training like a mad man, nor am I doing nothing- I do honestly make an effort with my fitness) If I may begin with an example : When I FIRST started running and focusing on my fitness, in my naiveté I started out running 2 miles at a pace that allowed to me run the distance. I had no dramas with making the distance, and after experimenting with the pace a bit, I upped with another 2 mile lap, and again, then again - All within a very short space of time. I mention this as this really wasn't that long ago in the grand scale of things, and it shows that although I was going about it wrong, I made some big improvements. Skip to recent months, and the problem becomes clear. In December/ January - My shortest run was a 5k- One steady away, one fast-er paced at the end of the week with a 3 mile fartlek run in-between. Some weeks I threw in a 6, maybe 8 miler. Since then, I have been feeling fatigue in a way I've actually never experienced before - Breathing very heavily on runs, panting at the end of a very short distance, having to stop, add to that some creeping pain on the shins and I've suddenly started to flake out faster and under less mileage within the past 6 weeks or so. All came to a head the other week when I failed a PFT. (Something I have never done, consistently around the 9:15 mark. And even when I did my RSW with little to no training, I came in under 10:30, for Christ's sake) For an ending example, skip to the 'run' I had today - Barely managed to make 2 miles, at a 9:00 mile pace. Had to stop for 2 minutes to get my breath back, and jogged at a very steady away pace for another mile. Was literally wheezing at the end. I just can't fathom why this is - Less than 8 weeks ago, I was running as fine as I ever have. I haven't put on weight, haven't lost any. No dramatic changes in diet. Had no time off from training, nor have I purposefully reduced my mileage or time spent running. All discussion, ideas and pisstakings are warmly welcomed and encouraged, Many thanks.